
John Isner of the United States hits a return to Novak Djokovic of Serbia during their men's singles quarterfinal at the China Open tennis tournament in Beijing, China, Oct. 9, 2015. Isner lost the match 0-2. (Xinhua/Xing Guangli)

John Isner of the United States hits a return to Novak Djokovic of Serbia during their men's singles quarterfinal at the China Open tennis tournament in Beijing, China, Oct. 9, 2015. Isner lost the match 0-2. (Xinhua/Xing Guangli)