Ana Ivanovic, who rose to No 1 in the world after her 2008 French Open victory, is excited to take on resurgent Serena Williams for a US Open quarterfinal berth as she continues her own climb back to the game's summit.

"It's exciting," said Ivanovic, who advanced to the last 16 with a 6-3, 6-4 victory over American Sloane Stephens.

"I think she's the hottest player out there at the moment. It is going to be a good challenge."

Williams, who toppled fourth seed Victoria Azarenka of Belarus 6-1, 7-6 (5) to reach the fourth round, is seeded 28th thanks to the slide in her ranking that followed an 11-month layoff.

"It is a tough draw to play her fourth round," said Ivanovic, ranked 19th. "She's favorite, that's for sure. But I am playing good and I enjoy competing again. I can give her a tough match."

Ivanovic, 23, has been working since June with Nigel Sears, former head of women's tennis at the Lawn Tennis Association, as she tries to rebuild a career that once saw her atop the rankings.

By reaching the last 16 she matched her best appearance in any Grand Slam over the past two years.

She said her third-round clash with Sloane under the floodlights of the massive Arthur Ashe Stadium was a fun return to the game's spotlight.

"I was really excited," she said. "Nerves do play a part a little bit, also playing against an American girl, crowd favorite. But I had a really good time out there."

She'll be even more up against it when she meets three-time US Open champion Williams for a place in the last eight, but Ivanovic insisted she was up to the challenge against a player who has won both of their prior encounters.

"Maybe I can go for revenge on Monday," she said.