Ivanovic undaunted by Serena challenge

NEW YORK: Ana Ivanovic, who rose to number one in the world after her 2008 French Open victory, is excited to take on resurgent Serena Williams for a US Open quarter-final 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 (7/5) 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, currently ranked 19th. "She's favourite, 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 in the past two years.