Lucas Pouille of France serves to Nick Kyrgios (not pictured) of Australia in the first round match of the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 15 August 2016. EPA/TANNEN MAURY

Ana Ivanovic of Serbia serves to Donna Vekic (not pictured) of Croatia in the first round match of the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 15 August 2016. EPA/TANNEN MAURY

David Ferrer of Spain hits a return shot to Julien Benneteau of France in their first round match of the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 15 August 2016. EPA/TANNEN MAURY

Lesia Tsurenko of Ukraine hits a return shot to Shuai Zhang (not pictured) of China in the first round match of the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 15 August 2016. EPA/TANNEN MAURY

Grigor Dimitrov of Bulgaria serves to Gilles Simon of France in their first round match of the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 15 August 2016. EPA/TANNEN MAURY