Serbia's Novak Djokovic reacts after the match against Switzerland's Stanislas Wawrinka at the quarter final tennis match at the Swiss Indoors tournament on November 6, 2009 in...

U.S. Andy Roddick receives treatment from medical personnel during a match against Stanislas Wawrinka of Switzerland at the Shanghai ATP Masters 1000 tennis tournament in Shanghai, China, Tuesday, Oct. 13...

Rafael Nadal of Spain returns a ball during an exhibition match against Stanislas Wawrinka (unseen) of Switzerland at The Hurlingham Club in West London, England, on June 19, 2009. AFP...

Roger Federer of Switzerland reacts during his match against Stanislas Wawrinka of Switzerland during their third round match of the Monte Carlo Tennis Masters tournament in Monaco...

...Murray of Great Britain looks on prior to the men's singles fourth round match against Stanislas Wawrinka of Switzerland on Day Seven of the Wimbledon Lawn Tennis Championships at the All England Lawn...

...Murray of Great Britain looks on prior to the men's singles fourth round match against Stanislas Wawrinka of Switzerland on Day Seven of the Wimbledon Lawn Tennis Championships at the All England Lawn...

Spain's Rafael Nadal reacts during an exhibition match against Switzerland's Stanislas Wawrinka, in which Nadal lost at the Hurlingham Club, in London, Friday June 19, 2009

Spain's Rafael Nadal reacts after an exhibition match against Switzerland's Stanislas Wawrinka which Nadal lost at the Hurlingham Club in London, Friday June 19, 2009.(AP Photo/Akira...

Swiss Roger Federer hits a return to his Swiss opponent Stanislas Wawrinka during the Monte-Carlo ATP Masters Series Tournament tennis match, on April 16, 2009 in Monaco...

Roger Federer of Switzerland plays a return to fellow countryman Stanislas Wawrinka during the third round match of the Monte Carlo Tennis Masters tournament in Monaco, Thursday, April...

KEY BISCAYNE, FL - MARCH 31: Rafael Nadal of Spain returns a shot against Stanislas Wawrinka of Switzerland during day nine of the Sony Ericsson Open at the Crandon Park Tennis Center...

INDIAN WELLS, CA - MARCH 18: Novak Djokovic of Serbia throws his racquet while playing Stanislas Wawrinka of Switzerland during the BNP Paribas Open at the Indian Wells Tennis Garden March 18, 2009...

...States' Andy Roddick, right, talks with coach Patrick McEnroe during Roddick's match against Switzerland's Stanislas Wawrinka in their Davis Cup tennis match at the Birmingham-Jefferson Convention Complex Arena in Birmingham, Ala...

BIRMINGHAM, AL - MARCH 07: Bob Bryan returns a shot to Stanislas Wawrinka and Yves Allegro of Switzerland while playing with Mike Bryan during the third rubber of their...

BIRMINGHAM, AL - MARCH 07: Bob Bryan returns a shot to Stanislas Wawrinka and Yves Allegro of Switzerland while playing with Mike Bryan during the third rubber of their...