Flushing Meadows, NY (My Sportsbook) - The feel-good story of the 2009 U.S. Open continued on Monday when 17-year-old American Melanie Oudin toppled yet another seeded Russian to reach her first-ever Grand Slam quarterfinal.

The 70th-ranked Oudin outlasted 13th-seeded Nadia Petrova 1-6, 7-6 (7-2), 6-3 on Labor Day at the Billie Jean King USTA National Tennis Center. The upstart Oudin shocked fourth-seeded former U.S. Open runner-up Elena Dementieva in the second round and took out 29th-seeded former champion Maria Sharapova in the third here. The diminutive American dropped the first set in her last three matches before mounting gutsy comebacks.

Oudin is now 4-0 at this fortnight, with all the victories coming against Russians. She topped a promising Anastasia Pavlyuchenkova in the opening round last week.

It appeared as though Petrova was going to end Oudin's Cinderella run here, as the Russian led 6-1, 4-3 on Day 8, but Oudin refused to go away.

Oudin fought back to take the second set via tiebreak, which she dominated, and then simply controlled play in the third. The American broke Petrova to open the final stanza and recorded another key break to assume a commanding 5-2 cushion.

The Marietta, Georgia native Oudin wound up converting on a third match point when she popped a cross-court forehand winner to cap the upset in 2 hours, 27 minutes. Petrova committed 27 more unforced errors (59-32) than her American counterpart and both players tallied seven service breaks apiece in the entertaining affair.

Another fourth-round win came for another surprise in the draw, Kateryna Bondarenko. The Ukrainian lambasted Argentine Gisela Dulko in double-bagel fashion on Monday, 6-0, 6-0.