Stanislas Wawrinka of Switzerland returns the ball to Juan Monaco of Argentina during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 15 April 2015. EPA/SEBASTIEN NOGIER

Marcel Granollers of Spain returns the ball to Tommy Robredo of Spain during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 15 April 2015. EPA/SEBASTIEN NOGIER

Rafael Nadal of Spain in action against Lucas Pouille of France during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 15 April 2015. EPA/SEBASTIEN NOGIER

Tomas Berdych of Czech Republic returns the ball to Sergiy Stakhovsky of Ukraine during their second round match at the Monte-Carlo Rolex Masters tournament tennis in Roquebrune Cap Martin, France, 15 April 2015. EPA/SEBASTIEN NOGIER

Roger Federer of Switzerland returns the ball to Jeremy Chardy of France during their second round match at the Monte-Carlo Rolex Masters tennis tournament in Roquebrune Cap Martin, France, 15 April 2015. EPA/SEBASTIEN NOGIER