Johan Kriek (born April 5, 1958) is a South African-American professional male tennis player and founder of the Global Water Foundation, a non-profit organization dedicated to delivering clean water to the world's neediest communities.
 Kriek won two Australian Opens and reached the semifinals at the French Open and US Open, as well as the quarterfinals of Wimbledon.
 He won 14 professional singles and 8 doubles titles, reaching a career-high singles ranking of World No. 7.
 Kriek's most memorable wins include victories over Andre Agassi, Jimmy Connors, John McEnroe, Guillermo Vilas, Stefan Edberg, Michael Chang, Vitas Gerulaitis and Björn Borg.
Glenn Layendecker (born May 9, 1961) is a former professional tennis player from the United States.
 His highest singles ranking was World No. 48 in 1990.
 His highest doubles ranking was World No. 32.
 Layendecker's career wins included Andre Agassi, Michael Chang, Yannick Noah, Aaron Krickstein, Anders Järryd, and Brad Gilbert in singles matches.
 He also beaned John McEnroe in the temple with an approach shot at the US Open.
John McEnroe and Patrick McEnroe were the defending champions, but Patrick McEnroe did not participate.
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Guy Forget and Henri Leconte were the defending champions but lost the final to John McEnroe and Patrick McEnroe, 7–6, 6–3.
Patrick John McEnroe (born July 1, 1966) is a former professional tennis player and the former captain of the United States Davis Cup team.
Michael Te-Pei Chang (born February 22, 1972) is a retired American professional tennis player.
 He won 34 top-level professional singles titles, including the 1989 French Open when he was 17.
 He also was a three-time runner-up at the majors and reached a career best ranking of world No. 2 in 1996.
 Since he was shorter than virtually all of his opponents, he played a dogged defensive style utilizing his quickness and speed.
 In 2008, he was inducted into the International Tennis Hall of Fame, and he has coached Kei Nishikori since 2014.
Stefan Edberg was the defending champion and retained his title, defeating Pete Sampras 3–6, 6–4, 7–6, 6–2 in the final to win the men's singles title at the 1992 US Open.
 The semifinal between Edberg and Michael Chang was a battle wherein Edberg won in five sets after 5 hours and 26 minutes, then the longest match in the Open Era.
 This is also where John McEnroe and Jimmy Connors played their last Grand Slams.
John McEnroe and Mark Woodforde were the defending champions but only Woodforde competed that year with Patrick McEnroe.
John McEnroe and Patrick McEnroe were the defending champions, but were eliminated in the round-robin stage.
John McEnroe and Patrick McEnroe were the defending champions.
 John McEnroe did not participate this year.
 Patrick McEnroe partnered Richey Reneberg, losing in the second round.

Question: Michael Chang and Patrick McEnroe were both what?
Answer: professional tennis player