Poland's Agnieszka Radwanska secured the last remaining spot in the season-ending WTA tennis Championships without hitting a ball after Marion Bartoli retired from her Kremlin Cup quarter-final with an illness.
Kremlin Cup organisers said the Frenchwoman was forced to withdraw from her match against Russia's Elena Vesnina after suffering from a viral infection.
World number nine Bartoli was the only player with a chance of catching the eighth-ranked Pole but she needed to win in Moscow to clinch a place in the eight-player field in Istanbul.
Russia's top seed Vera Zvonareva, who has already booked her ticket to Turkey, was upset by eighth-seeded Slovak Dominika Cibulkova 4-6 6-4 6-4 after nearly a three-hour battle.
Cibulkova now faces Vesnina, ranked number 64 in the world, in Sunday's semi-finals.
Despite losing her opening match in Moscow, Radwanska will join world number one Caroline Wozniacki, Maria Sharapova, Victoria Azarenka, Wimbledon champion Petra Kvitova, Zvonareva, US Open champion Samantha Stosur and French Open champion Li Na in Istanbul next week.