NEW YORK, UNITED STATES: Football star quarterback Joe Montana (L) tennis star Andre Agassi (C) and hockey great Wayne Gretzky (R) stop and pose for photographers before the...

...FL - DECEMBER 11: Andy Roddick answers questions from the media prior to the Andy Roddick Foundation Celebrity Tennis Match at the Polo Club of Boca Raton December 11, 2005 in Boca Raton, Florida

NEW YORK - AUGUST 28: James Blake attends a charity event benefiting the Thomas Blake, Sr. Memorial Cancer Research Fund at Las Chicas Locas on August...

LONDON, ENGLAND - NOVEMBER 24: Roger Federer of Switzerland serves the ball during the men's singles second round match against Andy Murray of Great B...

...Nadal of Spain 6-4, 6-4, in a Singles match during the Barclays ATP World Tour Tennis Finals in London, on November 23, 2009. AFP PHOTO/GLYN KIRK (Photo credit should read GLYN KIRK...

...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

...Federer, 7-5, 6-4, in a second round match at the Western & Southern Financial Group Masters tennis tournament, Wednesday, Aug. 16, 2006, in Mason, Ohio

LONDON, ENGLAND - NOVEMBER 23: Rafael Nadal of Spain reacts after the men's singles first round match against Robin Soderling of Sweden during the Bar...

...a point against Rafael Nadal of Spain in a Singles match during the Barclays ATP World Tour Tennis Finals in London, on November 23, 2009. AFP PHOTO/GLYN KIRK (Photo credit should read GLYN KIRK...

LONDON, ENGLAND - NOVEMBER 23: Robin Soderling of Sweden returns the ball during the men's singles first round match against Rafael Nadal of Spain dur...

...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

...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

...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...

...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...

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...