Melanie Oudin continued her giant-killing run at the US Open when she knocked out a third Russian seed in succession.

The 17-year-old world number 70 from Marietta, Georgia, had already eliminated fourth seed Elena Dementieva and former champion Maria Sharapova, the No. 29 and she returned to Arthur Ashe Stadium to come from a set down to add 13th seed Nadia Petrova to her list of victims and reach the last eight.

The American teenager had been in tears after beating Sharapova but she was all business in beating Petrova 1-6 7-6 (7-2) 6-3 in front of a wildly enthusiastic New York crowd enjoying an extra day off for Labour Day.

"It's kind of hard to explain how I've done it," Oudin said. "There are no tears because I believed I could do it and it's like now that I know that I do belong here.

"This is what I want to do and I can compete with these girls no matter who I'm playing.

"I have a chance against anyone."

Oudin will be able to put that to the test in a quarter-final against the winner of the night match between the only remaining seeds in her half of the draw, 2004 winner Svetlana Kuznetsova, the reigning French Open champion and sixth seed, and ninth seed Caroline Wozniacki of Denmark

"I don't really care who I get," Oudin said. "I'm happy to be in the quarter-finals. I know it's going to be a tough match no matter who I play."

Petrova is backing compatriot Kuznetsova to face Oudin but with the American having already beaten four tall Russians - her first round victory was over world number 36 Anastasia Pavlyuchenkova - the ousted 13th seed said she should expect something different.

"Now she gets hopefully a short and a little chubby Russian," Petrova joked. "See how she's going to handle that."

The day had begun in a decidedly lower key at Ashe when unseeded Ukrainian Kateryna Bondarenko whitewashed Argentina's Gisela Dulko 6-0 6-0 in just 47 minutes.

"I don't know what to tell you," Bondarenko said. "I'm surprised that it's six-love, six-love but I'm really happy it went that way."

At least one semi-finalist in the women's draw will be unseeded as Bondarenko's quarter-final opponent will be Belgium's Yanina Wickmayer, a 4-6 6-4 7-5 winner over Dinara Safina's US Open conqueror Petra Kvitova.

Wickmayer, 19, has been based in Florida since she was nine having left Belgium following the loss of her mother to cancer.

She persuaded her father to sell up and move to the States where she trained at the Saddlebrook tennis academy.

"I still don't know how I did it when I was nine," she said. "I guess I was older than I thought I was.

"He always believed in me and supported me.

"He didn't leave everything because he expected me to be a champion. Actually he just left everything to make me happy. That's a whole lot of difference."