(writes through with quotes, detail, late matches)
* Radwanska qualifies for WTA finals without playing
* Bartoli pulls out with illness
Agnieszka Radwanska secured the last remaining spot in the season-ending WTA Championships without hitting a ball after Marion Bartoli retired from her Kremlin Cup quarter-final with an illness on Friday.
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.
"I think my whole body needed a break," Bartoli said in a statement. "Yesterday, during my match I didn't feel very well but I still had energy left so it was enough to win."
The third seed had crushed unseeded Russia Ksenia Pervak 6-1 6-1 in just over an hour on Thursday to reach the last eight.
"This morning I had so much pain in my whole body, in my neck... I couldn't even warm up today. So I knew it would be very difficult," added Bartoli, who won her second title of the year on Sunday after beating U.S. Open champion Samantha Stosur in the Japan Open final.
"It has been a very long season and I really tried to play till the very end but that was it for me."
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 a near three-hour battle.
Despite losing her opening match in Moscow on Wednesday, Radwanska will join world number one Caroline Wozniacki, Maria Sharapova, Victoria Azarenka, Wimbledon champion Petra Kvitova, Zvonareva, Stosur and French Open champion Li Na in Istanbul next week.
Zvonareva blamed a sore shoulder for her defeat.
"I started having pain in my shoulder in the second set and I started thinking about it and was afraid it would get worse," the world number five told reporters.
"I've tried to fight through the pain but just couldn't get it done. I probably should have stopped," she added.
"I have this bad habit -- I often keep on playing even when I have an injury and it doesn't do me any good."
Cibulkova said she was unaware of Zvonareva's problems.
"I didn't notice she was having any problem," said the Slovak, who now faces 64th-ranked Vesnina in Saturday's semi-finals.
"She kept serving at top speed so I was very surprised she had called for a trainer midway through the third set."
The second semi-final pits Estonian Kaia Kanepi, who crushed Russia's sixth seed Svetlana Kuznetsova 6-1 6-2, against Czech Lucie Safarova, a 6-4 6-4 winner over Russian Vera Dushevina. To query or comment on this story email firstname.lastname@example.org)