Andy Murray of Britain in action against Jeremy Chardy of France during their fourth round match for the French Open tennis tournament at Roland Garros in Paris, France, 01 June 2015. EPA/ETIENNE LAURENT

Alison Van Uytvanck of Belgium reacts as she plays against Andreea Mitu of Romania during their fourth round match for the French Open tennis tournament at Roland Garros in Paris, France, 01 June 2015. EPA/CAROLINE BLUMBERG

A ballboy rests as Flavia Pennetta of Italy plays against Garbine Muguruza of Spain during their fourth round match for the French Open tennis tournament at Roland Garros in Paris, France, 01 June 2015. EPA/ETIENNE LAURENT

Roger Federer of Switzerland in action against Gael Monfils of France during their fourth round match for the French Open tennis tournament at Roland Garros in Paris, France, 31 May 2015. EPA/YOAN VALAT

Novak Djokovic of Serbia in action against Richard Gasquet of France during their fourth round match for the French Open tennis tournament at Roland Garros in Paris, France, 01 June 2015. EPA/ROBERT GHEMENT

Lucie Safarova of Czech Republilc in action against Maria Sharapova of Russia during their fourth round match for the French Open tennis tournament at Roland Garros in Paris, France, 01 June 2015. EPA/ROBERT GHEMENT