Roger Federer of Switzerland returns to Novak Djokovic of Serbia in the men’s final of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/JONATHAN BRADY

Novak Djokovic of Serbia serves to Roger Federer of Switzerland in the men’s final of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/FACUNDO ARRIZABALAGA

Novak Djokovic of Serbia in action against Roger Federer of Switzerland during their final match for the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/TOBY MELVILLE

Roger Federer of Switzerland plays Novak Djokovic of Serbia in the men’s final of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/FACUNDO ARRIZABALAGA

Novak Djokovic of Serbia in action against Roger Federer of Switzerland during their final match for the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/JONATHAN BRADY

Roger Federer of Switzerland celebrates a set point winner against Novak Djokovic of Serbia in the men’s final of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/FACUNDO ARRIZABALAGA

Novak Djokovic of Serbia returns to Roger Federer of Switzerland in the men’s final of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/JONATHAN BRADY

Roger Federer of Switzerland in action against Novak Djokovic of Serbia during their final match for the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/TOBY MELVILLE

Roger Federer of Switzerland celebrates with the runners up trophy after losing against Novak Djokovic of Serbia during their final match for the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/ANDY RAIN

Novak Djokovic of Serbia celebrates with the trophy after winning against Roger Federer of Switzerland during their final match for the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 12 July 2015. EPA/ANDY RAIN