Lleyton Hewitt
Roger Federer and probably Pete Sampras
Sorry I don't know anymore for sure.
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Amended answer
Tennis was not on the list of Olympic sports from 1928-1984.Upon resumption the men's singles champions are as follows;
1988 Miroslav Mecir.
1992 Marc Rossett.
1996 Andre Agassi.
2000.Yevgeniy Kafelnikov.
2004.Nicolas Massu.
2008.Rafael Nadal.
1996
The mens singles winner was Novak Djocovik and the mens doubles winners were Rick de Voest and Dmitry Tursunov. The womens singles winner was Venus Williams and the womens doubles winners were Cara Black and Liezel Huber.
Marty Reason
USTA Billie Jean King National Tennis Center at Flushing Meadows, New York, USA.
Rafael Nadal has won the most number of singles title at French Open.
The first official tournement was the mens singles in 1877 won by Spencer Gore
After the London Olympics 2012 the current number one world ranked player in the Mens is Zhang Jike from China. He is a gold medalist in the 2012 Olympic Men's singles and men's teams, gold medalist in the 2102 World teams championships, winner of the 2011 mens singles in the world championships and 2011 Men's world cup winner.
The Australian Open Men's Singles in 1981 was won by Johan Kriek, who beat Steve Denton in the final.
1996 Mens Singles Quarterfinal between Pete Sampras and Alex Corretja of Spain.
The "Gentlemen's" singles title was won by John Newcombe, of Australia, in straight sets - 6-3, 6-1, 6-1.
John Pius Boland of Great Britain at the 1896 Games in Athens.
For the 2010 Fench Tennis Open total prize money was €16,807,400. Prize money was split €7,580,800 mens singles, doubles & qualifiers and €7,481,600 womens singles, doubles & qualifiers. The additional amount was split between 3 Legends Trophies (Women, Over 45 & Under 45), Mixed Doubles, Wheelchair Singles & Doubles and Accomodation. The largest prize was €1,120,000 for each of the mens and womens singles winners. The smallest prize was €1,000 per team (€500 per player) for the mens and womens wheelchair doubles semi-finalists.