NEW YORK - They are both ahead of schedule.

Maria Sharapova is progressing quickly on one track that might make her a champion again, while Melanie Oudin is speeding on another that gets her mentioned in the same sentence with Sharapova.

Oudin, the 17-year-old American, pieced together the biggest upset of the first week of the U.S. Open on Thursday, while Sharapova, still working her way back into shape from her shoulder injury, avoided that fate.

Next, the two will meet in a third-round match in which the toughest task might belong to the fans at Flushing Meadows: deciding who to cheer for.

“The whole thing was just amazing. I can’t believe I won,” Oudin said after her 5-7, 6-4, 6-3 victory over No. 4 Elena Dementieva.

Among the early winners Friday were 10th-seeded Flavia Pennetta and No. 22 Daniela Hantuchova on the women’s side, and No. 7 Jo-Wilfried Tsonga in the men’s draw.

Oudin added the Dementieva win to an upset she pulled off against former No. 1 Jelena Jankovic at Wimbledon.

Her quest for the next shocker comes against Sharapova, who is only No. 29, though there’s a growing sense that the Russian, a three-time major champion, is playing better than that.

Sharapova defeated another 17-year-old American, Christina McHale, 6-2, 6-1 during the night session at Arthur Ashe Stadium. Sharapova has lost a total of six games in two matches this week.

“I certainly think I’m playing a lot better than I was when I first got back,” she said. “I feel like the belief in the game, the confidence, is coming back.”

She has some other good things going for her. One is that Grand Slam tournaments normally provide players with a day of rest between matches — good news for the shoulder that kept her out for nearly 10 months.

Just as significant is that Dementieva and Jankovic, another upset victim Thursday, were on her side of the draw. That side is headlined by top-seeded Dinara Safina — who struggled through her second straight unimpressive, three-set victory Thursday — and missing, quite notably, both the Williams sisters, who play their third-round matches Friday.

“Just because other people are struggling doesn’t make me a bigger contender,” Sharapova said. “I’m a contender when I’m in the draw. That’s the way I look at it. Other people’s struggles don’t make my draw, or anything else in my path to a Grand Slam easier.”

Indeed, before she starts thinking about winning her second U.S. Open, she must deal with Oudin, who has moved up to 70th in the rankings, which makes her the third-best American in women’s tennis.

She wears pink and yellow shoes with the word “Believe” stamped on the outside of the heels. While it’s getting easier to believe with every big win she puts up, nobody in her camp expected it all so soon.

“I knew she’d always make the top 10 or 20,” said her mother, Leslie. “I did know that. But not now. Maybe when she hit 21 or something.”

Or sooner if she keeps going like this.

Her match against Dementieva, who has been playing well of late, was hardly a rollover. It included a medical break to tape up her left leg, which has been bothering Oudin for most of the summer. She started crying after the break, and guessed the leg got worse because of the magnitude of the event.

“First time playing on Arthur Ashe, I was beating No. 4 in the world, about to beat her,” Oudin said. “Just a little bit of everything. A lot of things were going through my mind.”

She had three match points at 5-3 and started cringing after Dementieva saved the first two with winners off aggressive points. Oudin placed the serve at 40-30 hard into the backhand corner and Dementieva couldn’t get it back.

The Russian, the 2008 Olympic gold medalist still in search of her first Grand Slam title, said she did not give the match away.

“She was in the court, not afraid to play, playing very aggressively, really enjoying this atmosphere and the crowd support,” Dementieva said. “It looks like she has a good future.”

Slide show Super Sharapova Check out images of Maria Sharapova's career on, off court. more photos

While the women’s draw had its upsets, the men’s side went to form, and Americans played a big role in that.

No. 5 Andy Roddick, No. 21 James Blake and No. 22 Sam Querrey all won, as did 55th-ranked John Isner and 276th-ranked Jesse Witten. Robby Ginepri and Taylor Dent are also still in the draw, meaning Labor Day weekend at the U.S. Open will have its share of American flavor.

“We’re all happy when the other Americans are doing well,” Blake said. “To compare us or to, or expect the same as what happened in years past, I think it’s been done a million times, and I’ve always said I think it’s a little unfair.”

In fact, there may never be another McEnroe or Connors, but that doesn’t mean America won’t ever see another fiery, inspiring player or two in the future.

For Oudin, it seems the future is now.

She plays Sharapova on Saturday, when she’ll try to capture imaginations and maybe even usurp the role normally played by the Russian superstar who now calls America home.

“I think that’s totally understandable,” Sharapova said. “We’re in New York City. I’m a Russian playing against a young, up-and-coming girl who has a tremendous amount of potential. I think it would be strange if they weren’t rooting for her.”

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