
Frances Tiafoe of the United States celebrates after scoring during the men's singles first round match against Roger Federer of Switzerland at the 2017 US Open tennis tournament in New York, the United States, Aug. 29, 2017. (Xinhua/Wang Ying)

Frances Tiafoe of the United States celebrates after scoring during the men's singles first round match against Roger Federer of Switzerland at the 2017 US Open tennis tournament in New York, the United States, Aug. 29, 2017. (Xinhua/Wang Ying)