Kei Nishikori of Japan returns the ball during the men's singles fourth round match against Roger Federer of Switzerland at the Australian Open Tennis Championships in Melbourne, Australia, Jan. 22, 2017. Nishikori lost 2-3. (Xinhua/Lui Siu Wai)
Kei Nishikori of Japan returns the ball during the men's singles fourth round match against Roger Federer of Switzerland at the Australian Open Tennis Championships in Melbourne, Australia, Jan. 22, 2017. Nishikori lost 2-3. (Xinhua/Lui Siu Wai)