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

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