Elena Rybakina qualified for the WTA Finals' last four, beating an error-prone Iga Swiatek 3-6, 6-1, 6-0 on Monday, while Amanda Anisimova beat fellow American Madison Keys 4-6, 6-3, 6-2 in Riyadh.
World No. 2 Swiatek made 36 unforced errors in the last two sets while Rybakina made 17, with the Kazakh player getting her first win over the six-time Grand Slam champion in their last five meetings.
Rybakina, who beat Anisimova on Saturday, reached the semifinals after her second straight win.
With your current subscription plan you can comment on stories. However, before writing your first comment, please create a display name in the Profile section of your subscriber account page.