Li Na of China had to battle from behind in each set on Wednesday to beat Russia's Maria Kirilenko 6-4, 7-6 (4) in the second round of the New Haven Open, the final WTA tournament before the US Open.

The French Open champion had trailed 1-3 in the first set and 1-4 in the second, before securing the straight-set win and a berth in the quarterfinals, where she will meet Russian Anastasia Pavlyuchenkova, who downed Italy's Roberta Vinci 6-2, 6-4.

Marion Bartoli, seeded fourth, also progressed to the last eight, beating Czech Klara Zakopalova 6-2, 2-6, 6-1. The Frenchwoman will next face another Czech, qualifier Petra Cetkovska. Unseeded Spaniard Anabel Medina Garrigues moved into the quarters, overcoming a knee injury to win 6-2, 7-6 (5) win over Elena Vesnina of Russia. He next opponent will be Italian Francesca Schiavone.

Li, the first Asian to win a grand slam event, has beaten Kirilenko four of the five times they have met. But, she said, the Russian, like most of her opponents since the French Open, seemed to be a bit more focused this time.

"Everyone thinks different," she said. "Before (it was), 'Oh, OK, I beat her.' But now, if they win, 'Oh, I beat a French Open champion.' They are even more excited."

Li took the first set after breaking Kirilenko in the seventh game, which went to deuce four times. She also broke Kirilenko in the seventh game of the second set to get back on serve. She then won four straight points in the tiebreaker for a 6-2 cushion.

She will next face another Russian, Anastasia Pavlyuchenkova, who beat Roberta Vinci of Italy, 6-2, 6-4 after jumping out to a 5-1 lead early.

In North Carolina, Andy Roddick advanced to the quarterfinals in the Winston-Salem Open, beating Santiago Giraldo 6-1, 6-3 in the final men's tuneup before the US Open.

Roddick was in sharp form for the second match in a row and showed signs that he might be recovered from recent injuries in time for the last grand slam event of the year. This was just his third match in the last six weeks because of an abdominal strain.

"That's the biggest thing for me, not to be scared of extended rallies," Roddick said. "You have to get your legs back and there's only one way, and that's jumping in."

Roddick and John Isner are the lone Americans remaining in the draw. Fourth-seeded Isner beat No. 13-seeded Jarkko Nieminen 7-6 (4), 6-2.

In the quarterfinals, Isner will face Marcos Baghdatis, who beat Steve Darcis 7-5, 6-0. Third-seeded Alexandr Dolgopolov advanced by beating Bulgaria's Grigor Dimitrov 6-4, 1-6, 7-6 (7). He will face the Netherlands' Robin Haase, who defeated Pierre-Ludovic Duclos 6-4, 7-5. Ninth-seeded Sergiy Stakhovsky upset No. 5 Nikolay Davydenko 6-4, 6-4 to set up a quarterfinal against French qualifier Julien Benneteau, who Russia's Igor Andreev 2-6, 6-1, 7-6 (5).