Roger Federer (bottom) of Switzerland serves the ball to Guillermo Garcia Lopez of Spain during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 12 April 2016. EPA/SEBASTIEN NOGIER

Pablo Carreno Busta of Spain returns the ball to Jo Wilfried Tsonga of France during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 12 April 2016. EPA/SEBASTIEN NOGIER

Andy Murray of Great Britain returns the ball to Pierre Hugues Herbert of France during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 12 April 2016. EPA/SEBASTIEN NOGIER

Jo Wilfried Tsonga of France returns the ball to Pablo Carreno Busta of Spain during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 12 April 2016. EPA/SEBASTIEN NOGIER

Borna Coric of Croatia returns the ball to Philipp Kohlschreiber of Germany during their first round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 12 April 2016. EPA/SEBASTIEN NOGIER