Australia's Samantha Stosur says her thrilling victory over Elena Dementieva on Sunday was one of the most exciting matches of her career.

Stosur saved four match points from the Russian No.12 seed in a see-sawing third set in the fourth round of the US Open, fighting back from 3-5 down to serve for the match at 6-5.

But Dementieva broke the No.5 seed's serve, sending the match to a tiebreak.

The big-hitting Australian powered her way to an early 3-0 lead, and Dementieva's nerves finally got the better of her as she hit a forehand long on match point to concede victory to Stosur in two hours and 38 minutes.

Stosur paid tribute to a vocal Australian supporter group in the grandstands for helping her through the epic encounter, which concluded at 1.35am - a new late-finish record for a women's match at Flushing Meadows.

"I feel unbelievable right now," Stosur said in an on-court interview.

"We both played a great match. We both went for it. To have a match like that here is fantastic."

"That's definitely one of the most exciting matches I've ever played."

"It's always tough to follow the men, but it was a great atmosphere out here. When everyone stays and cheers, it couldn't be better."

"I just dug deep and never gave up and made her work for it and I was able to pull it out."

Stosur advances to the quarter-finals at the US Open for the first time but now faces defending champion Kim Clijsters, who looked in ominous form as she dismantled former world No.1 Ana Ivanovic in straight sets on Saturday.

"I guess I've got to recover as best I can and be ready to play," Stosur said.

"I think the last year-and-a-half I've been playing much better and really found my confidence and belief."

"So to come here and get my best result ever is great."

"Hopefully I can keep it going. It's not going to be easy but I'll give it my best and hopefully everyone will come out and support us."

Stosur will take on Clijsters for a place in the semi-finals on Tuesday.