Coco Gauff and Taylor Fritz powered the U.S., tournament winner two years ago, into the semifinals of the United Cup mixed teams tennis event on Wednesday. In the first singles match, Gauff had a 7-6 (4), 6-2 win over China's Zhang Shuai. Fritz then made sure of victory for the U.S. by edging Zhang Zhizhen 6-4, 6-4.