Anisimova, ranked No. 4, had also eliminated Swiatek in the U.S. Open quarterfinals.
Anisimova got the first break of serve in the contest to take the second set to force a decider. She faced only four break points and saved each one.
Elena Rybakina, who had already advanced to the semifinals, completed her round-robin phase with a 6-4, 6-4 victory over Ekaterina Alexandrova.
Rybakina and Anisimova will learn their semifinal opponents after Thursday’s final round-robin matches: top-ranked Aryna Sabalenka plays defending champion Coco Gauff; and Jessica Pegula faces Jasmine Paolini, who has already been eliminated.
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AP tennis: https://apnews.com/hub/tennis
