MOSCOW — Defending champion Elena Dementieva defeated Nadia Petrova 6-4, 4-6, 7-6 (6) Friday to advance to the semifinals of the Kremlin Cup.

Vera Zvonareva defeated Dominika Cibulkova of Slovakia, 7-5, 6-4.

Petrova went 4-3 up in the all-Russian match with a break in the seventh game of the first set, but Dementieva won three consecutive games to take the set. Dementieva was leading 4-1 in the second set but Petrova rallied to win five consecutive games.

In the third, Dementieva again took a 4-1 lead but Petrova rallied back to 4-4 and each player held serve to force a tiebreaker. Dementieva won on her third match point.

"It was not an easy match," Dementieva said. "There were many missed chances for me."

Dementieva will play the winner of the match between top-ranked Jelena Jankovic and Flavia Pennetta.

Seventh-seeded Zvonareva saved five break points in the 10th game of the first set before breaking Cibulkova in the next game to win the set. Two breaks early in the second set secured her a berth in her first semifinal after five quarterfinal appearances in her home town event.

In men's quarterfinals, veteran Fabrice Santoro won the first set 6-3 and was 2-0 up in the second when his fellow Frenchman Paul-Henri Mathieu, seeded fourth, retired because of illness.

Santoro, who will turn 36 in December, won his only title this season in Newport in July.

Mischa Zverev rallied from 5-1 down in the third set to advance to his first career ATP Tour semifinal with a 6-4, 3-6, 7-5 victory over Viktor Troicki.