Sports

Oudin Cinderella story rolls on

Melanie Oudin added another chapter to her fairy-tale U.S. Open.

Oudin, the unseeded 17-year-old spark plug from Marietta, Ga., who has won the hearts of Flushing with a string of upset victories, bulled her way into the quarterfinals yesterday with yet another dramatic three-set win, 1-6, 7-6 (2), 6-3, over No. 13 seed Nadia Petrova at a raucous Ashe Stadium.

Oudin becomes the youngest woman into the Open quarterfinals since eventual titlist Serena Williams in 1999. This year also marks the 30th anniversary of 16-year-old Tracy Austin’s U.S. Open win at Forest Hills.

“Now I know that I do belong here,” Oudin said. “I can compete with these girls no matter who I’m playing. I have a chance against anyone.”

Oudin’s unflappable game eventually wore down Petrova, as it did two other Russians, No. 4 Elena Dementieva and No. 29 Maria Sharapova, in three-setters the previous two rounds. At 5-foot-6, Oudin is not a knockout artist, but she jabs relentlessly and she finished ahead on all the scorecards. Call it a unanimous decision.

“I’m not giving up at all,” Oudin said. “If they’re going to beat me, they’re going to have to beat me, because I’m not going anywhere.”

With the capacity crowd cranking up the decibels, and her twin sister Katherine joining her parents courtside, Oudin gathered steam as the match went on and Petrova slowly came unhinged.

“I don’t actually mean to lose the first set,” Oudin said with a laugh. “I just sometimes start off slowly, I guess.”

Petrova’s serve, which carried her through the first set in summary fashion, deserted her in the match’s crucial moments. She double-faulted on break point early in the third set to put Oudin up 3-2, dropped her serve again for 5-2, and a third straight time in the decisive game, as the spunky American blistered a forehand crosscourt to convert her third match point.

“I was losing it because I could see every emotion on her face,” Katherine said. “I’ve never seen a match like this before. That’s the main difference between us — she’s strong mentally and I’m not.”

Melanie’s mental toughness was on full display as she clawed back from down a break in the second. She evened the set at 4-4, served out two gutsy holds, then blitzed Petrova in the tiebreak, winning the first five points en route to a 7-2 win.

“The first set is purely a warmup set,” said her father, John.

Oudin the comeback kid improved to an astounding 17-4 in three-set matches this year.

America’s latest tennis sweetheart will face Danish 19-year-old Caroline Wozniacki in tomorrow’s quarterfinals, likely under the lights at Ashe. Wozniacki rallied to knock off sixth-seeded Svetlana Kuznetsova 2-6, 7-5, 7-6 (3) last night.

“Hopefully some from the crowd will cheer for me,” Wozniacki said.

Don’t count on it.

jlehman@nypost.com