- Agnieszka Radwanska claims eighth and final spot in WTA Championships in Istanbul
- Poland's Radwanska qualifies after France's Marion Bartoli pulls out in Moscow
- Bartoli could have overtaken Radwanska by winning the Kremlin Cup
- Top seed Vera Zvonareva crashes out to Dominika Cibulkova in the quarterfinals
Poland's Agnieszka Radwanska has secured the final place in the eight-strong field for the WTA Championships in Istanbul next week after illness ended the hopes of her closest rival.
Radwanska was sweating on the performance of Marion Bartoli at the Kremlin Cup this week after her second round exit from the same tournament.
But France's Bartoli, who needed to win the Moscow title to overtake Radwanska in the rankings and claim the last spot, withdrew from her quarterfinal Friday against home hope Elena Vesnina, citing a viral infection.
Bartoli, who won a WTA event in Japan last weekend, had swept aside Russia's Ksenia Pervak 6-1 6-1 in her second-round match Thursday.
Radwanska had soared up the rankings with back-to-back titles at the Pan Pacific Open in Tokyo and the China Open, and needed only to beat Lucie Safarova in her opener in the Russian capital to seal her place in the end-of-season finale.
She lost in three sets but after Bartoli's pull-out can now look forward to battling out for the prestigious title in the $5 million event in Turkey.
"I'm so happy to finally qualify for the championships as one of the top eight singles players," she said.
"Just a few weeks ago I didn't think I had a chance of qualifying and am now so happy to end my season in Istanbul."
She completes a field that features Caroline Wozniacki, Maria Sharapova, Petra Kvitova, Victoria Azarenka, Li Na, Vera Zvonareva and Samantha Stosur.
Meanwhile in other Kremlin Cup action, top seed and home favorite Vera Zvonareva was beaten by Dominika Cibulkova of Slovakia 4-6 6-4 6-4 in their quarterfinal match.
Eighth seed Cibulkova will play Vesnina in Saturday's opening semifinal, while Safarova will take on Kaia Kanepi.
Estonia's Kanepi eliminated sixth seed Svetlana Kuznetsova, beating the two-time grand slam champion 6-1 6-2, and Czech Safarova defeated another Russian, Vera Dushevina, 6-4 6-4.
At the WTA tournament in Luxembourg, top seed Azarenka of Belarus beat Czech Iveta Benesova 6-3 6-2 to breeze into the last four.
Azarenka will next play German sixth seed Julia Gorges, who went through when Latvia's Anastasija Sevastova retired hurt at 5-2 down in the opening set.
British qualifier Anne Keothavong continued her fine run as she overcame 23-year-old Dutch debutant Bibiane Schoofs 6-3 6-2.
Keothavong, who beat former world number one Ana Ivanovic in the previous round, plays Romania's Monica Niculescu in her first semifinal since the same tournament last year.
In the men's Kremlin Cup event, top seed Janko Tipsarevic will play three-time winner Nikolay Davydenko in Saturday's semis.
The Serbian beat Davydenko's fellow Russian Dimitry Tursunov 6-4 6-2, while the fourth seed overcame Germany's Michael Berrer 6-3 6-2.
Defending champion Viktor Troicki kept alive hopes of an all-Serbian final by winning a titanic struggle with American fifth seed Alex Bogomolov Jr. , eventually triumphing 7-6 (8-6) 6-7 (1-7) 7-6 (7-1).
He earned a clash with France's Jeremy Chardy, who beat Philipp Kohlschreiber of Germany 6-4 6-3.
In Sweden, top seed Gael Monfils set up a Stockholm Open semifinal with Canada's Milos Raonic after winning 7-5 7-5 against another big-serving player, Kevin Anderson of South Africa.
Sixth seed Raonic, who like his 10th-ranked French opponent is on the comeback trail after injury, beat Bulgaria's Grigor Dimitrov 7-5 6-4 as he sent down 14 aces.
The winner of their semi will face either two-time runner-up Jarkko Nieminen of Finland or America's two-time champion James Blake in Sunday's final.
Blake, who beat Nieminen in the 2006 final, had a walkover when Argentina's former world No. 3 David Nalbandian pulled out with a hamstring injury.