Djokovic beats Sousa 3-0 in U.S. Open men's singles 4th round

Novak Djokovic of Serbia serves during the men's singles fourth round match against Joao Sousa of Portugal at the 2018 US Open in New York, the United States, Sept. 3, 2018. Djokovic won 3-0. (Xinhua/Li Muzi)