New Zealand tennis ace Marina Erakovic is savouring the biggest grand slam win of her career after ousting former champion and two-time major winner Svetlana Kuznetsova from the US Open.

Erakovic, the world No.82, rallied for a thrilling 3-6 6-2 7-6 (7-3) first-round victory over the 2004 champion on Tuesday.

“It’s definitely one of those memorable ones. It was very tough out there and I thought the quality of tennis was very high,” Erakovic told AAP.

“In the third set, I was down but I felt I was in it still and I just had to keep playing.

“It was just a big mental and physical effort today and I’m pleased I got through it.”

Without a main-draw win in six previous visits to Flushing Meadows, Erakovic now has a golden opportunity to make the third round.

The 26-year-old next plays another Russian, world No.56 Elena Vesnina, an opponent she’s beaten twice before.

“It’s just a matter of trying to be aggressive and dictating with my forehand as much as I can,” Erakovic said.

Erakovic had lost in the first round of qualifying in her past two tournaments, but had shown signs of form last month when she beat world No.36 Bojana Jovanovski en route to the semi-finals of a Challenger event in Washington DC.

“I lost a couple of tight ones in New Haven and Cincinnati,” she said.

“I also started working with a new coach (Eduardo Nicolas) and we’ve been working on a few things and trying to implement those things.

“So I felt I was hitting the ball well coming here.”

Kuznetsova, the 20th seed, lamented playing too passively against the free-hitting underdog.

“She was more aggressive than I was and that was my mistake,” Kuznetsova said.

“I had high expectations of myself. I’ve been playing well.

“But she got loose, had nothing to lose and I was getting tighter and tighter.”