Carla Suarez Navarro of Spain in action against Jelena Ostapenko of Latvia during their first round match for the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 29 June 2015. EPA/ANDY RAIN

Roger Federer of Switzerland greets fans as he leaves following a training session for the All England Lawn Tennis Championships Grand Slam tournament in Wimbledon, London, Britain, 29 June 2015. The All England Lawn Tennis Championships will take place from 29 June until 12 July 2015. EPA/PETER KLAUNZER

Novak Djokovic of Serbia returns to Philipp Kohlschreiber of Germany during their first round match for the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 29 June 2015. EPA/FACUNDO ARRIZABALAGA

Serena Williams of USA inbetween games against Margarita Gasparyan of Russia in their first round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 29 June 2015. EPA/SEAN DEMPSEY

Maria Sharapova of Russia serves to Johanna Konta of Britain in their first round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, EPA/FACUNDO ARRIZABALAGA