Roger Federer of Switzerland returns the ball during the men's singles final match against Rafael Nadal of Spain at the Australian Open tennis championships in Melbourne, Australia, Jan. 29, 2017. (Xinhua/Bai Xue)
Roger Federer of Switzerland returns the ball during the men's singles final match against Rafael Nadal of Spain at the Australian Open tennis championships in Melbourne, Australia, Jan. 29, 2017. (Xinhua/Bai Xue)