(CNN) -- Ninth seed Caroline Wozniacki ousted sixth seed and French Open champion Svetlana Kuznetsova of Russia in a three-set, two-tiebreaker thriller at the U.S. Open.
Denmark's Caroline Wozniacki returns a point against Russian Svetlana Kuznetsova on Monday.
The 19-year-old Wozniacki reached the quarterfinals of a grand slam event for the first time, winning 2-6 7-6 (7-5) 7-6 (7-3) on Monday night.
The Dane overcame nine aces by Kuznetsova, the 2004 U.S. Open winner, and nearly four times as many winners -- 59 compared to Wozniacki's 16.
But Kuznetsova also reigned with unforced errors -- 63 compared with Wozniacki's 25.
"I hit too many unforced errors and I couldn't control my emotions. And I wanted it so much, so it was pretty hard to control," Kuznetsova, who saved two match-points, told the official U.S. Open Web site.
"All credit to her. But you can't win against anybody with those errors. No chance."
Wozniacki had been the highest-ranked player to have never reached the last eight at grand slam -- now world No. 18 Virginie Razzano of France has that dubious honor.
"I beat Svetlana, who is No. 6 in the world, and now I'm in my first Grand Slam quarterfinal, so it feels amazing," said Wozniacki, who reached the fourth round last year and has now won nine matches in a row following her victory at the tournament in New Haven.
"I just kept hanging in there. I stepped into the court a bit more in the second set and put more pressure on her. I'm really happy with this win."
Meanwhile, American teenager Melanie Oudin earlier continued her astonishing giant-killing run on Monday, eliminating 13th seed Nadia Petrova in three sets to reach the quarterfinals.
Oudin, ranked 70th in the world, has become the darling of the Flushing Meadows crowd, and she captivated the audience once again with a thrilling 1-6 7-6 (7-2) 6-3 success. Watch friends react to her success »
"I didn't think I started off too well and Nadia served unbelievable, but I stayed in there with her in the second set.
"She gave me a few free points and I got my confidence and then I believed I could do it," Oudin, 17, told reporters after completing her third comeback win in a row.
The win has made Oudin the youngest American to reach the last eight since Serena Williams 10 years ago, proving that her victories over Maria Sharapova and Elena Dementieva were no fluke.
"It was tough. She was all over me. I kept fighting and I got that break and I'm so happy that I won," added Oudin, her voice breaking with joy. "I'm so glad to be in my first grand slam quarterfinal."
Meanwhile, in another fourth-round match, Ukraine's Kateryna Bondarenko, crushed Argentina's Gisela Dulko 6-0 6-0 in just 47 minutes to avenge the South American's second-round defeat of her older sister Alona.
Bondarenko will now play Belgian teenager Yanina Wickmayer, who beat Czech Petra Kvitova -- the conqueror of top seed Dinara Safina -- 4-6 6-4 7-5 for a place in the semifinals.