(CNN) -- Jelena Jankovic was unable to claim consecutive Kremlin Cup titles after she was beaten 6-4 6-3 by Russian Alisa Kleybanova in the quarterfinals on Friday.
Jankovic failed to hold serve in the fifth game of each set and double-faulted twice to lose the match to Kleybanova, who is ranked 27th in the world.
The Serb had crucially already secured her berth in next week's season-ending WTA Championships in Doha.
The tournament in Moscow has a weakened women's draw because seven of the world's top players had already qualified but the world number nine insisted that she was not saving herself for the event.
Jankovic said: "It was a difficult match for me, I tried my best but she played better. I can't say I was holding back having already qualified for Doha, but sometimes it doesn't work out."
Kleybanova felt that she fully deserved her victory as she set up a semifinal match with Olga Govortsova of Belarus, who easily saw off Vera Dushevina of Russia 6-3 6-0.
"Of course, I'm very happy, but I've already beaten her once and I wanted to prove that that win was no fluke," Kleybanova told the tournament Web site.
"Last time we played I had to save match points in the second set before winning in three, so this time it was very important for me to beat her in two sets, to show that I'm a better player."
Elsewhere, Italian Francesca Schiavone defeated Russian Maria Kirilenko 6-3 6-2 and now faces Alona Bondarenko who had overcome Bulgarian Tsvetana Pironkova 6-3 6-3.
Meanwhile Kim Clijsters suffered her first defeat since winning the U.S. Open following her return to competitive tennis after she was beaten by Patty Schnyder at the Luxembourg Open.
The Belgian served up 11 double faults as she was beaten 6-4 3-6 7-6 (8-6) by her Swiss opponent, who will play Sabine Lisicki of Germany in the quarterfinals.
Fourth seed Daniela Hantuchova reached the last eight by edging past Czech opponent Lucie Hradecka 7-5 3-6 6-2.