NEW YORK -- American tennis has a fresh-faced new star, a 17-year-old who doesn't wear makeup or glamorous dresses, doesn't grunt, is thrilled to be driving a Toyota 4Runner, favors a cozy Irish pub to Manhattan's trendy restaurants and will be laying down sod at her suburban Atlanta tennis club when she comes down to earth from this wild U.S. Open ride.

Melanie Oudin, the gutsy teenager from Marietta, Ga., officially became the sport's newest sweetheart Saturday when she stunned former No. 1 Maria Sharapova 3-6, 6-4, 7-5 in front of a rowdy stadium court audience to advance to the fourth round. Her surprising run through this tournament is captivating the sport's imagination, much like then-17-year-old Sharapova did at Wimbledon five years ago and 14-year-old Jennifer Capriati did at the U.S. Open nearly 20 years ago.

``Oudin! Oh My!'' the stadium announcer yelled as the teenager tried to hold back tears. When she finally sat in her chair, as the crowd cheered, she cried into her towel.

``I don't even know what to say right now, thank you so much for cheering for me,'' said Oudin, who wears pink and yellow sneakers with the word ``Believe'' stamped on the side. ``I just kept fighting as hard as I could, kept trying as hard as I could, and I just can't even believe it.''

Later she added: ``Getting to play Maria was an unbelievable experience. She's such a great competitor. I just had a blast playing there [Saturday]. I learned, once again, that I can compete with these top girls, and if I believe in myself and my game, then I can beat them.''

SHOWING SPUNK

Oudin proved to be ``an American spunksmeister,'' in the words of CBS commentator Mary Carillo.

Standing barely 5-6, Oudin used her speed and deceptive power to give the towering Russian fits. But more than anything, it was Oudin's guts that carried her to victory. Pumping her fist and screaming, ``C'mon!'' after every winning point, the 70th-ranked Oudin pulled off her second huge upset at the Open after knocking off No. 4 Elena Dementieva in the previous round.

Of course, Sharapova was more charitable than usual, committing 63 unforced errors and 21 double faults, a U.S. Open record. The three-time Grand Slam champion has been struggling in her comeback after nearly a year off with a shoulder injury. Her new, abbreviated serve motion failed her, and she was visibly crushed by the loss.

``I thought she played really well, certainly held her ground, but I still feel like I had my chances, even though it wasn't my best day,'' said Sharapova, her reddened eyes peeking out from under the bill of her ballcap. ``When you let those chances go, it's just frustrating. But, got to hand it to her. She played solid, made me hit a lot of balls. She has a great amount of potential, considering her age.''

Next up: another Russian, No. 13 Nadia Petrova.

Oudin plans to do what she did the past few matches -- ``pretend it's not Arthur Ashe Stadium, just pretend I'm practicing at the academy back home, playing one of my friends, so it's not a big deal, so I don't think about the whole occasion.''

SILENCING DOUBTERS

There were those who said Oudin was too short to succeed among the growing forest of 6-footers. She never listened. She and her twin sister, Katherine, who plays on her high school tennis team, took up the sport as 9-year-olds and Melanie was always the one who believed she could make the big leagues. Her idol is 5-5 Justine Henin, the retired Belgian and former No. 1.

``Justine proved that you don't have to be 6-foot-something to be No. 1,'' Oudin said. ``I like the way she played, using different shots and using the entire court. She figured out how to beat players that overpowered her, using variety and movement.''

ESPN analyst Pam Shriver admits she ``wasn't that impressed'' with Oudin when she saw her play a Federation Cup match in February, but she is very impressed with how the teen has improved. ``She just doesn't back down from the big moments. She is not in awe of anyone. And she has deceptive power and speed. It's great to be talking about a talented U.S. teenager.''

Oudin said the newfound success hasn't changed her. Though she will take home at least $85,000 in prize money, she has no plans to trade in her 4Runner. She planned to celebrate Saturday's victory with another visit to the midtown Irish pub she ate at the previous four nights. ``It's bringing her good luck,'' explained her longtime coach, Brian de Villiers. ``We're not telling anyone where the pub is because everyone will start going there.''

Among her growing list of fans: Andy Roddick.

``I love watching her,'' Roddick said. ``I like the way she constructs points. It's not just hitting the ball to one spot. She kind of works the slice in there. She competes. She moves really well. I've only been around her a little bit. I think we played an exhibition last year. But she seems like a sweetheart. I'm cheering for her.''

He's not alone.