Serena Williams, right, shakes hands with her sister Venus Williams, left, after their semifinal match at the Family Circle Cup tennis tournament in Charleston, S.C., Saturday, April 6, 2013. Serena won 6-1, 6-2. (AP Photo/Stephen Morton)
Serena Williams, right, shakes hands with her sister Venus Williams, left, after their semifinal match at the Family Circle Cup tennis tournament in Charleston, S.C., Saturday, April 6, 2013. Serena won 6-1, 6-2. (AP Photo/Stephen Morton)
Russia's Maria Sharapova celebrates after defeating Venus Williams of the U.S. in their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 18, 2013. (AP Photo/Dita Alangkara)
Russia's Maria Sharapova celebrates after defeating Venus Williams of the U.S. in their third round match at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 18, 2013. (AP Photo/Dita Alangkara)
Venus Williams waits to resume play during her match against Bethanie Mattek-Sands during the first round of play at the 2012 US Open tennis tournament, Tuesday, Aug. 28, 2012, in New York. (AP Photo/Charles Krupa)
Venus Williams waits to resume play during her match against Bethanie Mattek-Sands during the first round of play at the 2012 US Open tennis tournament, Tuesday, Aug. 28, 2012, in New York. (AP Photo/Charles Krupa)
Venus Williams hits a ball while playing in a World Team Tennis match between the Washington Kastles and the Kansas City Explorers, Washington D.C., Sunday, July 22, 2012. (Ryan M.L. Young/The Washington Times)
Venus Williams wipes her face during a match against Angelique Kerber, of Germany, at the U.S. Open tennis tournament on Thursday, Aug. 30, 2012, in New York. (AP Photo/Darron Cummings)
Venus Williams wipes her face during a match against Angelique Kerber, of Germany, at the U.S. Open tennis tournament on Thursday, Aug. 30, 2012, in New York. (AP Photo/Darron Cummings)
