Serena Williams of the USA reacts as she plays against Sara Errani of Italy during their quarterfinal match for the French Open tennis tournament at Roland Garros in Paris, France, 03 June 2015. EPA/YOAN VALAT

Ana Ivanovic of Serbia in action against Lucie Safarova of Czech Republic during their semifinal match for the French Open tennis tournament at Roland Garros in Paris, France, 04 June 2015. EPA/CAROLINE BLUMBERG

Spectators watching Ana Ivanovic of Serbia against Lucie Safarova of Czech Republic during their semifinal match for the French Open tennis tournament at Roland Garros in Paris, France, 04 June 2015. EPA/ROBERT GHEMENT

Lucie Safarova of Czech Republic reacts after winning against Ana Ivanovic of Serbia during their semifinal match for the French Open tennis tournament at Roland Garros in Paris, France, 04 June 2015. EPA/ETIENNE LAURENT

Timea Bacsinszky of Switzerland in action against Serena Williams of the USA during their semifinal match for the French Open tennis tournament at Roland Garros in Paris, France, 04 June 2015. EPA/IAN LANGSDON

Serena Williams of the USA reacts as she plays against Timea Bacsinszky of Switzerland during their semifinal match for the French Open tennis tournament at Roland Garros in Paris, France, 04 June 2015. EPA/ETIENNE LAURENT