MOSCOW (AP) -- Former No. 1 Ana Ivanovic and 2011 U.S. Open champion Samantha Stosur advanced to the Kremlin Cup quarterfinals with straight-sets victories Thursday, while top-seeded Alexandr Dolgopolov bowed out of the men's event.
The 11th-ranked Ivanovic broke 19-year-old Russian qualifier Valeria Solovieva three times in a 6-1, 6-4 victory, while Stosur struggled past Alize Cornet of France 7-6 (6), 7-5.
"It was a good match for me," said Ivanovic, whose opponent was playing in only her second WTA match. "It's never easy to play someone you haven't seen before as you don't know how they react in the different situations. But I'm happy I've managed to finish in good style."
Ivanovic, whose best result this season was a semifinal appearance at Indian Wells in March, will be playing in her fifth quarterfinal. The 2008 French Open champion is looking for her 12th career title.
Ivanovic will next face Serbian qualifier Vesna Dolonc, who advanced to her second career WTA quarterfinal by routing Romania's Simona Halep 6-1, 6-0.
Top-seeded Stosur prevailed on a first-set tiebreaker and, 5-4 and 40-15 down on her serve in the second set, saved three set points before making the decisive break in the 11th game. The ninth-ranked Australian wrapped up the victory with a passing backhand crosscourt shot on her first match point.
"We always play tough against each other," Stosur said. "But we didn't meet for a long time and we both seriously improved our tennis since our last meeting.
"Today I had plenty of opportunities and chances to finish the points off. And It was important to believe I was doing the right things and to receive the win as a reward."
In Friday's quarterfinals, Stosur will face Klara Zakopalova of the Czech Republic.
Seventh-seeded Maria Kirilenko, the only Russian left in the women's draw, rallied from 5-1 down in the first set to beat Yaroslava Shvedova of Kazakhstan 7-5, 6-4.
In the second round of the men's tournament, French qualifier Edouard Roger-Vasselin produced the biggest surprise of the event so far, saving four match points to beat Dolgopolov of Ukraine 6-3, 7-5, 7-6 (6).
"It was a very close and a tough match," Roger-Vasselin said. "I survived four match points but also missed several easy shots on my match point before winning the match."
The 20th-ranked Dolgopolov landed 10 aces to his opponent's eight and had two match points, leading 6-5 and 40-15 in the second set, and two more at 6-4 in the tiebreaker. The Frenchman clinched victory with a forehand down the line.
"It was tough for me to get into the match but then I had many chances in almost every game in the third set," Dolgopolov said. "Yet I failed to make a break. It was so simple - I missed my chances and he has capitalized on his only one."
Roger-Vasselin will next play Croatian veteran Ivo Karlovic, who served 16 aces to beat Alex Bogomolov Jr, 7-6 (11), 6-4, the last Russian left in the men's draw.
Jerzy Janowicz of Poland advanced to the quarterfinals by beating seventh-seeded Carlos Berlocq of Argentina 6-3, 6-4.