Alize Cornet of France celebrates after defeating Serena Williams of USA in their third round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2014. EPA/VALDRIN XHEMAJ

Angelique Kerber (L) of Germany and Kirsten Flipkens of Belgium shake hands after their third round match at the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2014. EPA/ANDY RAIN

Kei Nishikori of Japan returns to Simone Bolelli of Italy during their third round match of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2014. EPA/ANDY RAIN

Roger Federer of Switzerland celebrates his win over Santiago Giraldo of Colombia in their third round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2014. EPA/TATYANA ZENKOVICH

Ana Ivanovic of Serbia returns to Sabine Lisicki of Germany during their third round match of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2014. EPA/VALDRIN XHEMAJ

Roger Federer of Switzerland returns to Santiago Giraldo of Colombia in their third round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2014. EPA/TATYANA ZENKOVICH