Around 8 p.m. Monday, Iga Swiatek was holding up her Cincinnati Open championship trophy. Around 8 a.m. Tuesday, she was getting ready for her mixed doubles match at the U.S. Open in New York City.

Playing in the Fast Four scoring format, Ruud and Swiatek made quick work of their Tuesday double-header. After knocking out all-American pair Madison Keys and Frances Tiafoe, 4-1, 4-2, they beat Caty ...