Melanie Oudin, John Isner Emerge as America's Tennis Underdog Sensations

Unknown 17-yr-old leaves Russian powerhouses Sharapova and Petrova in her wake.

Sept. 7, 2009 — -- Two U.S. underdogs, two huge upsets in the tennis world.

Today, U.S.'s Melanie Oudin, 17, is bound for U.S. Open quarterfinals with another comeback victory, beating 13th-seeded Nadia Petrova 1-6, 7-6 (2), 6-3.

This amazing victory comes on the heels of upsets against fourth-seeded Elena Dementieva in the second round and former world No. 1 Maria Sharapova, who she defeated 3-6, 6-4, 7-5 in a marathon third-round match on Saturday.

While Marietta, Ga.'s Oudin was defeating Sharapova, John Isner, the 6-foot-9 underdog from North Carolina, stunned the tennis world by defeating fifth-ranked tennis superstar Andy Roddick with 38 aces in his 7-6 (3), 6-3, 3-6, 5-7, 7-6 (5), victory.

These two previously unknowns have become the unlikely stars of the U.S. Open by defeating some of the tournament's best and most well-known competitors.

As the 70th seed in the U.S. Open, Oudin was already an underdog, but after toppling three top Russian competitors, she's now being called the "darling of the tournament."

"Getting to play Maria was an unbelievable experience for me," Oudin said at a press conference Saturday.

"She's such a great competitor, a great player," the teen said. "I just had a blast playing there today. I proved to myself that I can compete with these top girls. And if I believe in myself and my game, then I can beat them."

Sharapova, a former world No. 1 who won the Open in 2006, struggled through the match with 21 double faults and 63 unforced errors.

"[Oudin] certainly held her ground," Sharapova said. "I still feel like I had my chances, even though it wasn't my best day. When you let those chances go, it's just frustrating. But I got to hand it to her. She really stuck to her game plan and played solid. She made me hit a lot of balls."

Tough Tests Ahead for New Tennis Stars

Isner, who towers over most of the men in the tournament, beat fifth ranked Roddick hours later to punch his own ticket to the tournament's fourth round, where he will face Spaniard Fernando Verdasco.

Isner even managed to best Roddick in serve speed, rocking a 140-mile-per-hour serve to Roddick-s 139-mile-per hour best of the match. Roddick is the world record holder for fastest tennis serve at 155 miles per hour, set during the 2004 Davis Cup.

"It's obviously, hands down, the biggest win of my career," Isner said of defeating Roddick. "Nothing even compares. To do it at the stage I did it on is pretty spectacular. Maybe it will sink in a little bit more tomorrow, but I know I can really do some damage here. So I'm not satisfied just yet."