...Switzerland plays against Fernando Verdasco of Spain in a Singles match during the Barclays ATP World Tour Tennis Finals in London, on November 22, 2009

...Belgium on day thirteen of the 2009 U.S. Open at the USTA Billie Jean King National Tennis Center on September 12, 2009 in the Flushing neighborhood of the Queens borough of New York City...

...serves a ball to Switzerland's Roger Federer during the final match at the Davidoff Swiss Indoors tennis tournament in Basel, Switzerland, Sunday, Nov. 8, 2009. (AP Photo/Keystone/Georgios Kefalas

Roger Federer, of Switzerland, returns the ball to Julien Benneteau, of France, during the BNP Masters indoor tennis tournament in Paris, Wednesday, Nov. 11, 2009

Roger Federer speaks during a press conference at the Davidoff Swiss Indoors tennis tournament in Basel, Switzerland, Sunday, Nov. 1, 2009. The ATP tournament will last until Sunday, Nov. 8...

...Belgium on day thirteen of the 2009 U.S. Open at the USTA Billie Jean King National Tennis Center on September 12, 2009 in the Flushing neighborhood of the Queens borough of New York City...

MIAMI - NOVEMBER 16: Andre Agassi signs copies of his autobiography at Temple Judea on November 16, 2009 in Miami, Florida. (Photo by Gustavo Caballer...

...celebrates his victory over French Gael Monfils at the end of their Paris Masters ATP tournament final tennis match on November 15, 2009 at the 'Palais Omnisports de Paris Bercy' in Paris. Djokovic won 6...

PARIS - NOVEMBER 12: Andy Murray of Great Britain in action during his match against Radek Stepanek of Czech Republic during the ATP Masters Series at...

PARIS - NOVEMBER 11: Roger Federer of Switzerland hits an overhed against Julien Benneteau of France during the ATP Masters Series at the Palais Omnis...

...States during day four of the 2009 U.S. Open at the USTA Billie Jean King National Tennis Center on September 3, 2009 in Flushing neighborhood of the Queens borough of New York City

...celebrates his victory over French Gael Monfils at the end of their Paris Masters ATP tournament final tennis match on November 15, 2009 at the 'Palais Omnisports de Paris Bercy' in Paris. Djokovic won 6...

...celebrates his victory over French Gael Monfils at the end of their Paris Masters ATP tournament final tennis match on November 15, 2009 at the 'Palais Omnisports de Paris Bercy' in Paris. Djokovic won 6...

Novak Djokovic of Serbia returns the ball to Robin Soderling of Sweden during the BNP Masters indoor tennis tournament in Paris, Friday, Nov. 13, 2009. Djokovic won 6-4, 1-6, 6-3.(AP Photo...

...match against Novak Djokovic of Serbia in the final during Day Seven of the Davidoff Swiss Indoors Tennis at St Jakobshalle on November 8, 2009 in Basel, Switzerland