Yuichi Sugita of Japan hits a return shot to Milos Raonic of Canada during their match in the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 18 August 2016. EPA/TANNEN MAURY

Jo-Wilfried Tsonga of France hits a return shot to Steve Johnson of the US during their match in the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 18 August 2016. EPA/TANNEN MAURY

Angelique Kerber of Germany hits a retun shot to Barbora Strycova of he Czech Republic during their match in the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 18 August 2016. EPA/TANNEN MAURY

Milos Raonic of Canada hits a return shot to Dominic Thiem of Austria during their guarterfinal match in the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 19 August 2016. EPA/TANNEN MAURY

Steve Johnson of the US reacts during his match against Jo-Wilfried Tsonga of France in the Western & Southern Open tennis championships at the Linder Family Tennis Center in Mason, near Cincinnati, Ohio, USA, 18 August 2016. EPA/TANNEN MAURY