Roger Federer of Switzerland in action against Marcel Granollers of Spain during their second round match for the French Open tennis tournament at Roland Garros in Paris, France, 27 May 2015. EPA/ETIENNE LAURENT

German fans watching Sabine Lisicki of Germany in action against Daria Gavrilova of Australia during their second round match for the French Open tennis tournament at Roland Garros in Paris, France, 27 May 2015. EPA/ROBERT GHEMENT

Simona Halep of Romania falls as she plays against Mirjana Lucic-Baroni of Croatia during their second round match for the French Open tennis tournament at Roland Garros in Paris, France, 27 May 2015. EPA/ETIENNE LAURENT

Gael Monfils of France in action against Diego Schwartzman of Argentina during their second round match for the French Open tennis tournament at Roland Garros in Paris, France, 27 May 2015. EPA/YOAN VALAT

The silhouette of Angelique Kerber of Germany playing against Ajla Tomljanovic of Australia during their second round match for the French Open tennis tournament at Roland Garros in Paris, France, 27 May 2015. EPA/ROBERT GHEMENT