Jo-Wilfried Tsonga of France serves the ball to Jan-Lennard Struff of Germany during their first round match at the Monte-Carlo Rolex Masters tournament in Roquebrune Cap Martin, France, 14 April 2015. EPA/SEBASTIEN NOGIER

David Ferrer of Spain returns the ball to Victor Estrella Burgos of the Dominican Republic during their second round match at the Monte-Carlo Rolex Masters tournament in Roquebrune Cap Martin, France, 14 April 2015. EPA/SEBASTIEN NOGIER

Tommy Robredo of Spain returns the ball to Andreas Seppi of Italy during their first round match at the Monte-Carlo Rolex Masters tournament in Roquebrune Cap Martin, France, 14 April 2015. EPA/SEBASTIEN NOGIER

General view of the secound round match between Novak Djokovic (L) of Serbia and Albert Ramos Vinolas of Spain for the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 14 April 2015. EPA/SEBASTIEN NOGIER

Grigor Dimitrov of Bulgaria returns the ball to Fernando Verdasco of Spain during their first round match for the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 14 April 2015. EPA/SEBASTIEN NOGIER