
Alexandr Dolgopolov of Ukraine serves during the men's singles fourth round match against Rafael Nadal of Spain at the 2017 U.S. Open in New York, the United States, Sept. 4, 2017. Rafael Nadal won 3-0 to enter the next round. (Xinhua/Qin Lang)

Alexandr Dolgopolov of Ukraine serves during the men's singles fourth round match against Rafael Nadal of Spain at the 2017 U.S. Open in New York, the United States, Sept. 4, 2017. Rafael Nadal won 3-0 to enter the next round. (Xinhua/Qin Lang)