Maria Sharapova of Russia returns a ball during the 2nd round match of women's singles tennis event against Laura Robson of Britain at London 2012 Olympic Games, London, Britain, July 31, 2012. Maria Sharapova won the match 2-0. (Xinhua/Tao Xiyi)

Maria Sharapova of Russia acknowledges the audience after winning the 2nd round match of women's singles tennis event against Laura Robson of Britain at London 2012 Olympic Games, London, Britain, July 31, 2012. Maria Sharapova won the match 2-0. (Xinhua/Tao Xiyi)

Maria Sharapova of Russia acknowledges the audience after winning the 2nd round match of women's singles tennis event against Laura Robson of Britain at London 2012 Olympic Games, London, Britain, July 31, 2012. Maria Sharapova won the match 2-0. (Xinhua/Tao Xiyi)

Maria Sharapova of Russia returns a ball during the 2nd round match of women's singles tennis event against Laura Robson of Britain at London 2012 Olympic Games, London, Britain, July 31, 2012. Maria Sharapova won the match 2-0. (Xinhua/Tao Xiyi)