Serena Williams holds the championship trophy, after she defeated her sister Venus to win the women's singles...

NEW YORK - SEPTEMBER 12: Serena Williams argues a call by the line judge which led to her disqualification during the Women's...

NEW YORK - SEPTEMBER 12: Serena Williams argues with a line judge during her Women's Singles Semifinal match against Kim Clijsters of...

NEW YORK - SEPTEMBER 12: Serena Williams (R) is disqualified for a foot fault during the Women's Singles Semifinal match against Kim...

Serena Williams of the US reacts to losing a point to Kim Clijsters of Belgium during their semifinal...

Serena Williams of the US returns to her sister Venus during their WTA Championships final tennis match at...

DOHA, QATAR - OCTOBER 28: Serena Williams of the USA plays a backhand against Venus Williams of the USA in their round robin...

Serena Williams of the US eyes the ball before returning it to Denmark's Caroline Wozniacki during their...

DOHA, QATAR - OCTOBER 28: Venus Williams of the United States stretches to hit a forehand against Serena Williams of the United States in their round robin match during...

US tennis champion Serena Williams returns the ball to her sister Venus during their Maroon Group match on the second day...

DOHA, QATAR - OCTOBER 25: (L-R) Serena Williams of United States, Svetlana Kuznetsova of Russia, Elena Dementieva of Russia, Victoria Azarenka of Belarus, Dinara...

1- June 30, 2009; London, ENGLAND; Serena Williams (USA) celebrates a point against Victoria Azarenka (BLR) on day eight of the 2009 Wimbledon Championships...

BEIJING, CHINA - OCTOBER 8: (CHINA OUT) Serena Williams of the US reacts in her third round match against Nadia Petrova of Russia during day...

KEY BISCAYNE, FL - APRIL 04: Victoria Azarenka of Belarus poses with the trophy after defeating Serena Williams to win the women's final of the Sony Ericsson Open at the Crandon Park Tennis...

BEIJING - OCTOBER 08: Serena Williams of USA returns a shot against Nadia Petrova of Russia in her third round match during...