NEW YORK (AP) -- It's right there on her shoes: "Believe." Melanie Oudin always has, though even she had to admit this latest accomplishment felt a bit overwhelming.
Maybe that helped explain why her leg was cramping, why the tears were falling, why the match points were slipping away toward the end of her U.S. Open upset over fourth-seeded Elena Dementieva on Thursday.
"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."
The 17-year-old from Marietta, Ga., ranked 70th in the world, won 5-7, 6-4, 6-3. She is now, by almost every account, the next great American hope in women's tennis.
She places this upset next to the one over No. 6 Jelena Jankovic at Wimbledon that catapulted her into the top 100.
That was on Court 3 in front of hundreds an ocean away. This was in Arthur Ashe Stadium in front of thousands in her home country.
"I think it means more to me, though, since this is the U.S. Open," Oudin said. "You know, I had the whole crowd cheering for me, so much support."
She played much of the third set with a heavy wrap on her left thigh, an injury she said shouldn't prevent her from returning in a few days to face either 29th-seeded Maria Sharapova or Christina McHale, a 17-year-old American just like her.
The United States has long been looking for depth in a talent pool that has consisted of Serena and Venus Williams dominating at the top, with not too much beyond them.
"They've been, like, my idols," Oudin said. "I'm really proud of that, to be the third-best American."
She started moving up the list at Wimbledon, where she became the youngest American to reach the fourth round since Jennifer Capriati in 1993.
Between then and now, she still had to go through qualifying to get into main draws in tournaments in the U.S. Somewhere in the midst of all that, her boyfriend prodded her into sticking the word "Believe" on her shoes.
"It seems to fit me well," she said.
Dementieva agreed. She committed 37 unforced errors, but insisted she did not hand the victory to Oudin. The Russian hit winners to stave off Oudin's first two match points.
"So I needed to go for a big serve, and it went in," Oudin said.
For a winner.
"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."
In the match next door at Armstrong Stadium, No. 1 Dinara Safina stayed alive in the quest for her first major, but in ugly fashion -- a 6-7 (5), 6-2, 6-3 victory over Germany's Kristina Barrois. Safina won despite 38 unforced errors and 15 double-faults in her second straight uncomfortably close match.
She is ranked first despite having never won a major and she did little in this match against the 67th-ranked player to cool the debate about whether she really belongs there.
No. 2 Serena Williams, going for her third major of the season, dispatched her opponent 6-1, 6-1 in 53 minutes in the final match Wednesday night in Arthur Ashe Stadium.
Safina, playing in a smaller venue for a Thursday matinee, needed 2 hours, 13 minutes, much of which looked like the 2-hour, 25-minute display she put on in her three-set opener against Olivia Rogowska.
"When you are playing on the court and you're fighting, maybe in some stages you're not playing your best," Safina said. "But you're still here and the crowd is supporting you and that just gives you another edge."
In other action Thursday, men's No. 20 seed Tommy Haas of Germany defeated American Robert Kendrick and 10th-seeded Fernando Verdasco also advanced, along with unseeded American Jesse Witten. On the women's side, No. 13 Nadia Petrova, No. 21 Zheng Jie and No. 24 Sorana Cirstea advanced, while No. 30 Alona Bondarenko joined Dementieva as the only other seeded player to lose.
Others scheduled to play Thursday were Americans James Blake and Sam Querrey in the afternoon and Andy Roddick in the evening.
The Williams sisters took the court for their opening match in doubles, answering the questions about whether Venus would play in that event because of her sore knee.