NEW YORK, Sept. 2 (Xinhua) -- Ninth seed Samantha Stosur advanced into the U.S. Open fourth round with an epic 7-6(5), 6-7(5), 7-5 victory over 24th seed Nadia Petrova on Friday's night session.
The big Russian pushed hard and forced a tense clash lasting three hours and 16 minutes, the longest women's match at the event since third-set tie-breakers were introduced.
Stosur won the contest on her fifth match point and the result meant the Australian progressed beyond the third round at a Grand Slam for the first time this year.
The Australian will next meet Russian 25th seed Maria Kirilenko, who routed American Christina McHale 6-2, 6-3, for a spot in the quarterfinals.
After dropping her opening service game, Stosur played some scorching tennis to jump to a 5-2 lead and served for the first set at 5-3.
However, she wobbled and was unable to take advantage of three set-points as Petrova fought her way back for a tiebreak.
Stosur again looked on top at 4-2 in the tiebreak but Petrova captured three straight points to take back the momentum.
Stosur got even by reeling off the next three points to take the set.
The Australian continued to pile the pressure on her opponent's serve and captured a break in the fifth game.
Serving for the match at 5-4, Stosur had her problems again with two wild shanks and a double fault.
The Australian pulled out two match points once but Petrova responded by playing some stunning tennis to level the scores at 5-5.
In the resulting tiebreak, Stosur saved two set points before Petrova forced the contest into a third set with an ace.
Gaining in confidence, Petrova broke Stosur's serve in the third game of the final set and held a 4-2 lead.
Stosur broke back in the eighth game to level the scores and saved a break point for a 5-4 lead.
With the tension ramping up on both players, Petrova survived two more match points to even the ledger at 5-5.
Stosur, leading 6-5, finally won the encounter on her fifth match point when Petrova netted her return.
In earlier matches, world No. 2 Vera Zvonareva, the runner up to Tim Clijsters last year, also squeezed into the fourth round after a hard fight against Spain's Anabel Medina Garrigues in a 6-4, 7-5 victory.
Zvonareva will next take on Sabine Lisicki of Germany, who earned a 6-0, 6-1 victory over American Irina Falconi.
2006 champion Maria Sharapova suffered a surprising defeat to Italy's Flavia Pennetta, who took down the third-seeded Russian 6-3, 3-6, 6-4.
Sharapova was the runner-up at Wimbledon earlier this summer and was coming off a title in Cincinnati last month.
The 26th-seeded Pennetta will follow her hard-earned upset with a fourth-round match against Peng Shuai of China, who ousted German Julia Goerges 6-4, 7-6(1).
