General view of the empty Center Court during the Italian Open tennis tournament at the Foro Italico in Rome, Italy, 14 May 2016. Play of the semi final matches was suspended due to rain. EPA/ETTORE FERRARI

Japanese Kei Nishikori returns the ball to Serbian Novak Djokovic during their semi final match for the Italian Open tennis tournament at the Foro Italico in Rome, Italy, 14 May 2016. EPA/CLAUDIO ONORATI

Madison Keys of the USA returns the ball to Garbine Muguruza of Spain during their semi final match of the Italian Open tennis tournament at the Foro Italico in Rome, Italy, 14 May 2016. EPA/ETTORE FERRARI

France’s Lucas Pouille returns the ball to Britain’s Andy Murray during their semi final match of the Italian Open tennis tournament at the Foro Italico in Rome, Italy, 14 May 2016. EPA/CLAUDIO ONORATI

Serena Williams of the USA celebrates a point against Irina-Camelia Begu of Romania during their semi final match of the Italian Open tennis tournament at the Foro Italico in Rome, Italy, 14 May 2016. EPA/ETTORE FERRARI