2021 U.S. Open: What to Watch on Saturday. Tennis, United States Open (Tennis), Barty, Ashleigh, Bencic, Belinda, Hsieh Su-wei, Djokovic, Novak, Nishikori, Kei, Sorribes Tormo, Sara, Raducanu, Emma (2002- ), Pegula, Jessica (1994- )