Question: Did Kevin Ullyett and Frederik Nielsen play in men's singles?

full_context: Document 1: Kevin Curren: Kevin Melvyn Curren (born 2 March 1958) is a South African-American former professional tennis player. He played in two Grand Slam singles finals and won four Grand Slam doubles titles, reaching a career-high singles ranking of World No. 5.
Document 2: Leoš Friedl: Leoš Friedl (born 1 January 1977 in Jindřichův Hradec) is an inactive Czech professional tennis player best known for his doubles play with František Čermák. He is coached by Lubomir Gerla. During his career, Friedl won 16 top-level doubles titles and the 2001 Wimbledon mixed doubles title with Daniela Hantuchová, where they beat Mike Bryan and Liezel Huber, 4–6, 6–3, 6–2.
Document 3: Mark Knowles: Mark Knowles (born 4 September 1971) is a former tennis player from the Bahamas, specialising in doubles tennis. He has won a number of Grand Slam tournaments, most notably partnering with Daniel Nestor. At various times between 2002 and 2005 he was ranked World No. 1 in doubles. He is a five-time Olympian.
Document 4: Goran Ivanišević: Goran Ivanišević (; born 13 September 1971) is a retired Croatian professional tennis player and current tennis coach. He is the only person to win the men's singles title at Wimbledon as a wildcard. He achieved this in 2001, having previously been runner-up at the championships in 1992, 1994 and 1998. Before the 2001 tournament, he was ranked 125th and after his victory he was 16th. His career-high singles ranking was World No. 2 (behind Pete Sampras) in 1994. He coached Marin Čilić from September 2013 to July 2016, leading Čilić to his biggest achievement to date, the 2014 US Open title.
Document 5: Fred McNair: Frederick V. McNair IV (born July 22, 1950 in Washington, D.C.) is a former professional tennis player from the United States who reached the World No. 1 doubles ranking in 1976. That year, he teamed up with Sherwood Stewart to capture the men's doubles titles at French Open, the German Open and the Masters. McNair was also a mixed doubles runner-up at the French Open in 1981, partnering Betty Stöve. In 1978, he was a member of the US team that won the Davis Cup. In nine years on the professional tour, McNair won 16 doubles titles. His career-high singles ranking was World No. 67.
Document 6: Kevin Ullyett: Kevin Ullyett (born 23 May 1972 in Salisbury, now Harare) is a former professional tennis player from Zimbabwe. His primary success on the tour was in men's doubles.
Document 7: 2006 Rogers Masters – Doubles: Wayne Black and Kevin Ullyett were the defending champions, but Black retired in 2006, and only Ullyett competed that year.
Document 8: Haroon Ismail: Haroon Ismail (born February 27, 1955 in Salisbury, now Harare) is a former tennis professional from Rhodesia and Zimbabwe.
Document 9: Roger Federer junior years: Swiss tennis player Roger Federer's main accomplishments as a junior player came at Wimbledon, where, in 1998, he won both the singles tournament over Irakli Labadze, in straight sets, and the doubles with Olivier Rochus, over the team of Michaël Llodra and Andy Ram, also in straight sets. In addition, Federer was a runner-up at the US Open Junior tournament in 1998, losing the final to David Nalbandian. Federer would go on to win four other junior singles tournaments in his career.
Document 10: Vitas Gerulaitis: Vytautas Kevin Gerulaitis (July 26, 1954 – September 17, 1994) was an American professional tennis player. In 1975, Gerulaitis won the men's doubles title at Wimbledon, partnering with Sandy Mayer. He won the men's singles title at one of the two Australian Open tournaments held in 1977 (Gerulaitis won the tournament that was held in December, while Roscoe Tanner won the earlier January tournament). Gerulaitis also won two Italian Open titles, in 1977 and 1979, and the WCT Finals in Dallas, in 1978.
Document 11: 2012 Wimbledon Championships – Men's Doubles: Bob Bryan and Mike Bryan were the defending champions, but lost to wildcards Jonathan Marray and Frederik Nielsen in the semifinals. Marray and Nielsen won the title defeating fifth seeded Robert Lindstedt and Horia Tecău who competed in their third consecutive Wimbledon final. Marray became the first British player to win the men's doubles at Wimbledon since Pat Hughes and Raymond Tuckey in 1936. Nielsen is only the second Danish winner of a Grand Slam title, following his own grandfather, Kurt Nielsen, who won the mixed doubles at the 1957 U.S. National Championships.
Document 12: Cara Black: Cara Black (born 17 February 1979) is a professional tennis player from Zimbabwe. She is primarily a doubles specialist, winning 60 WTA and 11 ITF titles in that discipline. A former no. 1 ranked women's doubles player in the WTA Rankings, she has won ten Grand Slam titles in women's doubles and mixed doubles combined. By winning the mixed doubles title at the 2010 Australian Open, Black became the third woman in the Open Era to complete a Career Grand Slam in mixed doubles (after Martina Navratilova and Daniela Hantuchová). Having won one singles title on tour, she also peaked at no. 31 in the singles rankings in March 1999.
Document 13: 2010 If Stockholm Open – Doubles: Bruno Soares and Kevin Ullyett were the defending champions. Ullyett retired from professional tennis in 2009.
Document 14: 2013 Wimbledon Championships – Men's Doubles: Jonathan Marray and Frederik Nielsen were the defending champions, but decided not to play together. Marray played alongside Colin Fleming, but lost to Robert Lindstedt and Daniel Nestor in the third round. Nielsen paired up with Grigor Dimitrov, but lost to Julien Benneteau and Nenad Zimonjić in the second round.
Document 15: Frederik Nielsen: Frederik Løchte Nielsen (born 27 August 1983) is a professional male tennis player. He is a former Wimbledon Men's Doubles champion, in 2012, and now competes mainly on the ATP Challenger Tour in both singles and doubles. Nielsen is coached by fellow Dane John Larsen and is a member of the Denmark Davis Cup team. His grandfather is former grand slam finalist Kurt Nielsen.
ground_truth: no