Claim: Steffi Graf was ranked No.1 in the world during World War II.
Evidence: Stefanie Maria `` Steffi '' Graf -LRB- -LSB- ˈʃtɛfiː ˈgʁa : f -RSB- ; born 14 June 1969 -RRB- is a German former tennis player , who was ranked world No. 1 during her career.
World War II -LRB- often abbreviated to WWII or WW2 -RRB- , also known as the Second World War , was a global war that lasted from 1939 to 1945 , although related conflicts began earlier.