Venus Williams of the US plays Maria Sakkari of Greece in their second round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2016. EPA/FACUNDO ARRIZABALAGA

Kei Nishikori of Japan returns to Julien Benneteau of France in their second round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2016. EPA/HANNAH MCKAY

Players in action on the courts during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2016. EPA/PETER KLAUNZER

Grigor Dimitrov of Bulgaria returns to Gilles Simon of France in their second round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2016. EPA/ANDY RAIN

Timea Bacsinzky of Switzerland plays Luksika Kumkhum of Thailand in their first round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2016. EPA/FACUNDO ARRIZABALAGA