Andy Murray of Great Britain reacts after defeating Roger Federer of Switzerland in the gold medal men's singles match at the All England Lawn Tennis Club in Wimbledon, London at the 2012 Summer Olympics, Sunday, Aug. 5, 2012. (AP Photo/Elise Amendola)
Andy Murray of Great Britain returns to Roger Federer of Switzerland during the gold medal men's singles match at the All England Lawn Tennis Club in Wimbledon, London, at the 2012 Summer Olympics, Sunday, Aug. 5, 2012. (AP Photo/Elise Amendola)
United States' Serena Williams, left, celebrates with partner Venus Williams, right, after defeating Czech Republic's Lucie Hradecka and Andrea Hlavackova in a women's doubles gold medal tennis match at the All England Lawn Tennis Club at Wimbledon, in London, at the 2012 Summer Olympics, Sunday, Aug. 5, 2012. (AP Photo/Victor R. Caivano)
** FILE ** Roger Federer of Switzerland leans on the net after he defeated Juan Martin del Potro of Argentina at the All England Lawn Tennis Club in Wimbledon, London at the 2012 Summer Olympics, Friday, Aug. 3, 2012. (AP Photo/Elise Amendola)
Serena Williams of the United States volleys against Maria Kirilenko, below, of Russia in their women's doubles semifinal match at the All England Lawn Tennis Club in Wimbledon, London at the 2012 Summer Olympics, Saturday, Aug. 4, 2012. (AP Photo/Elise Amendola)
Mike Bryan, right, and Bob Bryan, left, of the United States, celebrate after defeating Jo-Wilfried Tsonga and Michael Llodra of France in the men's doubles gold medal match at the All England Lawn Tennis Club at Wimbledon, in London, at the 2012 Summer Olympics, Saturday, Aug. 4, 2012. (AP Photo/Victor R. Caivano)
United States' Serena Williams returns a shot to Maria Sharapova of Russia in the women's singles gold medal match at the All England Lawn Tennis Club at Wimbledon, in London, at the 2012 Summer Olympics, Saturday, Aug. 4, 2012. (AP Photo/Elise Amendola)
Serena Williams of the United States returns a shot to Caroline Wozniacki of Denmark at the All England Lawn Tennis Club at Wimbledon, in London, at the 2012 Summer Olympics, Thursday, Aug. 2, 2012. (AP Photo/Mark Humphrey)
Roger Federer of Switzerland celebrates after defeating Juan Martin del Potro of Argentina at the All England Lawn Tennis Club in Wimbledon, London at the 2012 Summer Olympics, Friday, Aug. 3, 2012. (AP Photo/Elise Amendola)
Roger Federer of Switzerland returns to John Isner of the United States at the All England Lawn Tennis Club in Wimbledon, London at the 2012 Summer Olympics, Thursday, Aug. 2, 2012. (AP Photo/Elise Amendola)