FILE - In this Nov. 4, 2012, file photo, Serena Williams of the U.S. returns a serve from sister Venus during an exhibition tennis match at Ellis Park Indoor Arena in Johannesburg, South Africa. Williams has had surgery on her big toes and withdrew from an exhibition match against top-ranked Victoria Azarenka in Thailand in December. A medical certificate from Florida podiatrist Jeffrey Rockefeller says Williams "was treated for a chronic foot disorder which involved minor procedures on both of her great toes." (AP Photo/Themba Hadebe, File)
FILE - In this Nov. 4, 2012, file photo, Serena Williams of the U.S. returns a serve from sister Venus during an exhibition tennis match at Ellis Park Indoor Arena in Johannesburg, South Africa. Williams has had surgery on her big toes and withdrew from an exhibition match against top-ranked Victoria Azarenka in Thailand in December. A medical certificate from Florida podiatrist Jeffrey Rockefeller says Williams "was treated for a chronic foot disorder which involved minor procedures on both of her great toes." (AP Photo/Themba Hadebe, File)
