...match during the men's singles round robin match against Roger Federer of Switzerland during the Barclays ATP World Tour Finals at the O2 Arena on November 26, 2009 in London, England

...the ball through his legs against Roger Federer of Switzerland in a Singles match during the Barclays ATP World Tour Tennis Finals in London, on November 26, 2009

...Argentina gestures as he plays against Fernando Verdasco of Spain in a Singles match during the Barclays ATP World Tour Tennis Finals in London, on November 24, 2009

...during the men's singles second round match against Andy Murray of Great Britain during the Barclays ATP World Tour Finals at the O2 Arena on November 24, 2009 in London, England. (Photo by Julian...

Robin Soderling of Sweden plays against Rafael Nadal of Spain in a Singles match during the Barclays ATP World Tour Tennis Finals in London, on November 23, 2009

...reacts after the men's singles first round match against Robin Soderling of Sweden during the Barclays ATP World Tour Finals at the O2 Arena on November 23, 2009 in London, England. (Photo by Clive...

...ball during the men's singles first round match against Rafael Nadal of Spain during the Barclays ATP World Tour Finals at the O2 Arena on November 23, 2009 in London, England. (Photo by Julian...

Roger Federer of 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

...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, 2009. (AP Photo/Keystone/Georgios Kefalas

Serbian Novak Djokovic 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...

PARIS - NOVEMBER 11: Roger Federer of Switzerland hits an overhed against Julien Benneteau of France during the ATP Masters Series at the Palais Omnisports De Paris-Bercy on November 11, 2009 in Paris, France. (Photo...

...Murray of Great Britain in action during his match against Radek Stepanek of Czech Republic during the ATP Masters Series at the Palais Omnisports De Paris-Bercy on November 12, 2009 in Paris, France. (Photo...

Serbian Novak Djokovic 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...

Serbian Novak Djokovic 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...

...the ball to Czech Republic's Radek Stepanek during the semi final match at the Swiss Indoors ATP tennis tournament on November 7, 2009 in Basel. Djokovic won 6-7 (4/7), 7-5, 6...