NEW YORK — Maybe it all was a little too much, a little too soon for Melanie Oudin.

The 17-year-old from Marietta, Ga., kept erasing big deficits and upsetting older, taller, higher-ranked players at the U.S. Open, generating more and more interest in her magical ride.

Her gutsy play, aw-shucks approach and those pink-and-yellow sneakers with "BELIEVE" on the heels carried Oudin all the way to the quarterfinals at the American Grand Slam tournament. That's where her surprising story ended last night with a 6-2, 6-2 loss to No. 9-seeded Caroline Wozniacki of Denmark.

"It was a lot," Oudin conceded. "These past two weeks have been really different for me. I've gone from being just a normal, like, tennis player to almost everyone in the United States knowing who I am now."

Then, keeping a brave face, Oudin added: "I don't think that affected my tennis game tonight at all."

Perhaps. Still, facing Wozniacki in the sport's largest arena, playing under the bright lights in the big city, Oudin showed signs of shakiness at the start, dropping 14 of the first 18 points. Even the comeback kid couldn't recover from that.

"This has been a great experience for me. I had a great run here," the 70th-ranked Oudin told the crowd during an on-court interview right after the match, an honor usually reserved for the winner. "I hope to come back next year and do even better."

It'll be hard to top her 2009 U.S. Open.

With impressive court coverage and solid groundstrokes, the 5-foot-6 Oudin knocked off four more established players — including three-time major champion Maria Sharapova and Beijing Olympic gold medalist Elena Dementieva — to become the youngest quarterfinalist at Flushing Meadows since Serena Williams in 1999.

Making the tale even better: Oudin's last three victories each came after she dropped the first set. Plus, there was her wide-eyed, age-appropriate attitude: Everything was "cool" and "awesome," including meeting Roger Federer for the first time and finally getting to shake hands with Sharapova — only after beating her, of course.

Away from the court, there was heady stuff, too. Extra interviews and photo ops. Greetings from strangers on the street. Autograph-seekers in the hotel lobby.

"She's just had so much other activity going on that mentally she wasn't quite as focused as she should've been," said Oudin's mother, Leslie. "All this comes with experience, and she'll learn how to handle this better."

As Oudin's coach, Brian de Villiers, put it: "Yeah, I think, over time, the distractions might have gotten to her."

An additional distraction did not come to light until last night, when www.SI.com reported that Oudin's father, John, filed for divorce from Leslie in July 2008 on grounds of adultery. According to the report, John Oudin alleged in a sworn statement last month that his wife had an affair with de Villiers.

John Oudin was not in his daughter's guest box last night.

She made 43 unforced errors, 23 more than Wozniacki, who also was playing in her first major quarterfinal. In essence, Oudin ran smack-dab into a version of herself, a counterpunching baseliner who was far steadier on this night.

Wozniacki leads the women's tour in match victories this season and, while all of 19, is a relative veteran next to Oudin. Wozniacki is tied for the tour lead with three titles in 2009, including a hard-court tournament in New Haven, Conn., the week before the U.S. Open began, meaning she is on a 10-match winning streak.

Wozniacki never appeared intimidated by the hostile crowd of 23,881, most of whom waited and waited for a reason to roar for their girl.

"I'm sorry that I won against Melanie today," Wozniacki told the partisan fans, some of whom cheered when she double-faulted. "I know that many of you wanted Melanie to win."

Now the Dane will play her first Grand Slam semifinal against another 19-year-old, Yanina Wickmayer of Belgium. The 50th-ranked Wickmayer — never before past the second round at a major tournament — beat Kateryna Bondarenko of Ukraine, 7-5, 6-4.

The other women's semifinal tomorrow features two far more familiar names: defending champion Williams against 2005 champion Kim Clijsters.

The men's semifinals Saturday will include — no surprise here — Federer, who improved to 12-0 against Robin Soderling by beating the 12th-seeded Swede, 6-0, 6-3, 6-7 (6), 7-6 (6), last night. Federer, seeking a sixth consecutive U.S. Open title, extended his own record by reaching a 22nd straight Grand Slam semifinal.

Federer will put his 39-match Flushing Meadows winning streak on the line against No. 4 Novak Djokovic, who eliminated No. 10 Fernando Verdasco of Spain, 7-6 (2), 1-6, 7-5, 6-2.