John Isner of USA returns to Feliciano Lopez of Spain in their fourth round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/TATYANA ZENKOVICH

Eugenie Bouchard of Canada celebrates her win over Alize Cornet of France in their fourth round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/ANDY RAIN

Kevin Anderson of South Africa serves to Andy Murray of Britain in their fourth round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/ANDY RAIN

Andy Murray of Britain returns to Kevin Anderson of South Africa in their fourth round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/ANDY RAIN

Andy Murray of Britain celebrates after beating Kevin Anderson of South Africa in their fourth round match during the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/ANDY RAIN

Grigor Dimitrov of Bulgaria returns to Leonardo Mayer of Argentina during their fourth round of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/FACUNDO ARRIZABALAGA

Grigor Dimitrov of Bulgaria scores against Leonardo Mayer of Argentina during their fourth round of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/FACUNDO ARRIZABALAGA

Novak Djokovic of Serbia returns to Jo-Wilfried Tsonga of France in their fourth round of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 30 June 2014. EPA/ANDY RAIN EPA/ANDY RAIN