Top seed Vera Zvonareva crashed out in the second round of the Kremlin Cup in Moscow, handing the final place in the season-ending Tour Championship to Jelena Jankovic.
Three players were vying for the eighth and final spot in the lucrative tournament in Doha next week, but Poland's Agnieszka Radwanska was the first to fall by the wayside after crashing out in the opening round of the Moscow event.
And she was joined on the plane home by Zvonareva, who slumped 6-0 6-2 to qualifier Tsvetana Pironkova of Bulgaria.
It is the first time the world number 126 has made the quarter-finals this year, where she will take on Ukraine's Alona Bondarenko for a place in the last four.
"She is a good player and I knew that," Zvonareva said. "It's very difficult to play against her. She moves perfectly on the court, can hit the ball hard and can vary her tempo.
"I'm not in my best shape now and to beat her today I should have played more attentively.
"Maybe I'm even happy. Finally I will have time to restore my health and start the new season in full strength."
Safe in the knowledge that her place in Doha is now secured, last year's Kremlin Cup champion Jankovic booked her place in the last eight with a 7-6 6-3 victory over Czech Lucie Safarova.
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