user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: when is the us open tennis mens final 2011? 
Knowledge Triplets: The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjf0
The US Open (Tennis), time.recurring_event.instances, 1992 US Open
1961 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1942 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw7s
The US Open (Tennis), time.recurring_event.instances, 1905 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1990 US Open
1987 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vrc93
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgxz
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgxl
The US Open (Tennis), time.recurring_event.instances, 1948 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1989 US Open
The US Open (Tennis), time.recurring_event.instances, 1925 U.S. National Championships
m.0_ycbzm, tennis.tennis_tournament_championship.year, 2011
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsgc3
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhqm
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b437zn
1944 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vrcdp
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhrc
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw2v
The US Open (Tennis), time.recurring_event.instances, 1903 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1935 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw7h
The US Open (Tennis), time.recurring_event.instances, 1963 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqg_2
The US Open (Tennis), time.recurring_event.instances, 1908 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1923 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_5bw
The US Open (Tennis), time.recurring_event.instances, 1881 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhrh
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjd4
The US Open (Tennis), time.recurring_event.instances, 1954 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1987 US Open
The US Open (Tennis), time.recurring_event.instances, 1949 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1928 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1994 US Open
m.0_ycbsm, tennis.tennis_tournament_championship.year, 2011
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg2q
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw03
1994 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.011qzhgg
1992 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_63b
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw6n
The US Open (Tennis), time.recurring_event.instances, 1893 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1916 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtnw
The US Open (Tennis), time.recurring_event.instances, 1952 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1914 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1883 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1969 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqv04
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtph
The US Open (Tennis), time.recurring_event.instances, 1958 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsgch
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_5cr
1979 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1926 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1995 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxv_7
The US Open (Tennis), time.recurring_event.instances, 1934 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1956 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1899 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg4b
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vr_rr
The US Open (Tennis), time.recurring_event.instances, 1938 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhqh
The US Open (Tennis), time.recurring_event.instances, 1951 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1937 U.S. National Championships
2001 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
1957 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtmr
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtlh
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw88
2002 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 2008 US Open
The US Open (Tennis), time.recurring_event.instances, 1944 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgyl
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjf8
m.0_ycc9m, tennis.tennis_match.date, 2011-09-11
1959 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
2010 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw7w
The US Open (Tennis), freebase.valuenotation.has_no_value, Date of final occurrence
1991 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1929 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhqr
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjfd
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg36
m.0_ycckt, tennis.tennis_match.date, 2011-09-12
The US Open (Tennis), time.recurring_event.instances, 1922 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsgcm
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjf4
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhqw
The US Open (Tennis), time.recurring_event.instances, 1965 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1892 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw2q
The US Open (Tennis), time.recurring_event.instances, 1955 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhs7
The US Open (Tennis), time.recurring_event.instances, 1961 U.S. National Championships
1964 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjgx
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgyq
The US Open (Tennis), time.recurring_event.instances, 1998 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgxv
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqvdk
The US Open (Tennis), tennis.tennis_tournament.match_results, m.011r2s1m
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b43881
1999 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1913 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsqbc
1936 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1936 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg2v
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjcx
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vr_tb
The US Open (Tennis), time.recurring_event.instances, 1945 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhrr
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqg_6
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vq28n
The US Open (Tennis), time.recurring_event.instances, 1950 U.S. National Championships
2006 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqt2_
The US Open (Tennis), time.recurring_event.instances, 2011 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqvg1
The US Open (Tennis), time.recurring_event.instances, 1927 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw80
The US Open (Tennis), time.recurring_event.instances, 1920 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqt4m
The US Open (Tennis), time.recurring_event.instances, 1890 U.S. National Championships
1980 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b438h5
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjh0
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhsc
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqvfy
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_61g
The US Open (Tennis), time.recurring_event.instances, 1933 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_62d
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtn_
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vrc9w
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw8x
The US Open (Tennis), time.recurring_event.instances, 1991 US Open
2007 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
2003 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_622
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_61v
1995 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
m.0_ycbxh, tennis.tennis_tournament_championship.year, 2011
1973 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
m.0_ycbp1, tennis.tennis_tournament_championship.year, 2011
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b43808
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vq282
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgxq
The US Open (Tennis), time.recurring_event.instances, 1886 U.S. National Championship
m.0_ycckt, tennis.tennis_match.date, 2011-09-12
The US Open (Tennis), time.recurring_event.instances, 1918 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhph
The US Open (Tennis), time.recurring_event.instances, 1911 U.S. National Championships
2008 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1959 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhpm
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vr_s3
The US Open (Tennis), tennis.tennis_tournament.champions, m.04fgsgr
The US Open (Tennis), tennis.tennis_match.event, m.0_ycckt
The US Open (Tennis), time.recurring_event.instances, 1999 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw7x
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgzv
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_62v
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_61l
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw36
The US Open (Tennis), time.recurring_event.instances, 1898 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgx2
The US Open (Tennis), time.recurring_event.instances, 1904 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1931 U.S. National Championships
2013 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjh4
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b438dr
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw6v
m.0_ycbq_, tennis.tennis_tournament_championship.year, 2011
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsq7d
The US Open (Tennis), time.recurring_event.instances, 1988 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqvdf
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw2g
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjdd
1993 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1993 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjgd
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtlc
The US Open (Tennis), tennis.tennis_tournament.match_results, m.011qzhk6
The US Open (Tennis), time.recurring_event.instances, 1946 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgy2
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg32
The US Open (Tennis), time.recurring_event.instances, 1973 US Open
The US Open (Tennis), time.recurring_event.instances, 1957 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqt4r
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgwv
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_5br
1978 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw8s
The US Open (Tennis), time.recurring_event.instances, 1912 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqt2w
The US Open (Tennis), time.recurring_event.instances, 1921 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1940 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjdn
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_636
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjd8
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjd0
1963 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1939 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw7j
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vr_s7
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw8f
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjfn
The US Open (Tennis), time.recurring_event.instances, 2013 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b438fm
The US Open (Tennis), time.recurring_event.instances, 1962 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1897 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhrm
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtpc
1929 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
2011 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsgc7
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjgs
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgx6
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw2z
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw7n
The US Open (Tennis), time.recurring_event.instances, 1896 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjcs
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw6x
The US Open (Tennis), time.recurring_event.instances, 1924 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjg8
2012 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1885 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxvzr
The US Open (Tennis), time.recurring_event.instances, 1930 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1919 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vrcxr
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b4385t
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b52789
The US Open (Tennis), time.recurring_event.instances, 2012 US Open
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgwz
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgzz
2004 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsgc_
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vzw73
1997 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
1988 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
1989 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1964 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1932 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg46
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_628
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqvgy
1990 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vrcyh
m.0_ycc0b, tennis.tennis_tournament_championship.year, 2011
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqv00
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsgcr
The US Open (Tennis), time.recurring_event.instances, 1888 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg3b
1968 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
1954 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1966 U.S. National Championships
1965 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vsg3l
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw2b
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqgy6
The US Open (Tennis), time.recurring_event.instances, 1917 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vrcd1
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_5bc
The US Open (Tennis), time.recurring_event.instances, 1943 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1915 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhr7
The US Open (Tennis), time.recurring_event.instances, 1901 U.S. National Championships
1969 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vr_rk
1958 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_5b2
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vq247
The US Open (Tennis), time.recurring_event.instances, 1902 U.S. National Championships
2009 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqhrw
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_5b7
The US Open (Tennis), tennis.tennis_tournament.champions, m.09v_61q
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqv24
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqv20
The US Open (Tennis), time.recurring_event.instances, 1887 U.S. National Championships
m.0_ycc4s, tennis.tennis_tournament_championship.year, 2011
The US Open (Tennis), time.recurring_event.instances, 2010 US Open
The US Open (Tennis), time.recurring_event.instances, 1960 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.011r2s1y
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b4380x
The US Open (Tennis), time.recurring_event.instances, 2009 US Open
1998 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqtmm
The US Open (Tennis), time.recurring_event.instances, 1953 U.S. National Championships
The US Open (Tennis), time.recurring_event.instances, 1967 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.0b4387f
The US Open (Tennis), time.recurring_event.instances, 1910 U.S. National Championships
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw1v
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjdj
1976 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1947 U.S. National Championships
1974 US Open, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), time.recurring_event.instances, 1941 U.S. National Championships
1952 U.S. National Championships, time.event.instance_of_recurring_event, The US Open (Tennis)
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vqjfj
The US Open (Tennis), tennis.tennis_tournament.champions, m.09vxw7d
The US Open (Tennis), time.recurring_event.instances, 1894 U.S. National Championships

Answer: 2011-09-12