Serena Williams of the US returns to Ana Ivanovic of Serbia during their match at the US Open tennis tournament in New York, Sept 5, 2011. [Photo/Agencies]

NEW YORK - US powerful Serena Williams served nine aces to dispatch former world No 1 Ana Ivanovic in straight sets among gusty wind, advancing into the quarterfinal of US Open on Monday.

Williams, a 13-time major champion and three-time winner here, cruised through four rounds all in straight sets. The 28th seeded American proved a strong comeback and is tagged as a favorite for the tournament after a persuasive performance.

Williams beat the 2008 French Open champion of Serbia in 6-3, 6-4 and set up a quarterfinal clash against Russian Anastasia Pavlyuchenkova as the 17th seed rallied from one set down to defeat seventh seed Francesca Schiavone of Italy 5-7, 6-3, 6-4 in two hours and 41 minutes.

Ivanovic, 23, fell behind, 3-0, in eight minutes, but the Serb did not slip away. Despite serving eight double faults, Ivanovic had four more winners than Williams and won three games of her own to even the first set.

But it was one of those double faults, in the eighth game, that put Williams ahead, 5-3, and Williams served out the first set at love.

Williams also broke Ivanovic in the first game of the second set, an advantage she never lost. Williams served a 101-mph ace to end the match.

"It was really gusty out there, and in the wind it's always gonna be even tougher," said Ivanovic.

"In those kind of conditions, serve is the shot that it's gonna go away from both players. My serve broke down little more than hers did.

"I still created lots of opportunities and I felt I was stepping up a lot, and I just felt that was the biggest difference today."

"Even before the match, I think she's the favorite for the tournament. She's been playing really well, and it's gonna be tough," added the Serb.

Before Pavlyuchenkova knew it would be Williams she would face in the quarters, the 20-year-old said, "I don't know what to say about her. She's just awesome and a great athlete and she's showing good tennis so far. So I don't know what to say, really.

"I'm just going to go out there and - I'm going to say that I don't want to go out there and enjoy just being on the center court playing against Serena. I would like to do well, try to fight and with my effort I try to beat her. But of course I respect her a lot as well. She's just great."