NEW YORK — Venus Williams isn't having any trouble advancing at the U.S. Open, unlike many of the other top women's seeds.

The two-time Open champ beat No. 27 seed Alona Bondarenko of Ukraine 6-2, 6-1 on Saturday to move on to the fourth round. The seventh-seeded Williams has lost just 11 games in three straight-set wins.

Four of the top 10 women's seeds have lost, including No. 1 Ana Ivanovic. Williams and sister Serena are the only two former champs still alive in the draw.

Serena was set to play later Saturday. A win, and the sisters would be one victory away from a quarterfinal matchup.

Venus will face No. 9 seed Agnieszka Radwanska of Poland in the fourth round. Radwanska beat 18th-seeded Dominika Cibulkova of Slovakia 6-0, 6-3.

Radwanska defeated Williams in their lone meeting, a straight sets victory in Luxembourg in 2006.

"I'm looking forward to evening the score, I guess," Williams said. "She played well that time and I'm looking forward to continuing to move well and serve well."

Also scheduled to play later Saturday was men's No. 1 seed Rafael Nadal.

Third-seeded Svetlana Kutznetsova became the latest upset victim Friday when Katarina Srebotnik beat her 6-3, 6-7 (1), 6-3. She was one of two former Open champs to go down, as Lindsay Davenport also lost.

Olympic champion Elena Dementieva and No. 2 seed Jelena Jankovic advanced Friday, as did Novak Djokovic and Nikolay Davydenko on the men's side.

No. 8 seed Andy Roddick went from a big deficit late Friday night to a big lead in the wee hours of Saturday morning and, eventually, a 3-6, 7-5, 6-2, 7-5 victory over Ernests Gulbis of Latvia.

Perhaps it was no coincidence that Roddick turned things around so completely after spiking his equipment. He had just missed two groundstrokes to fall behind by a set and a break against a 40th-ranked kid who never has won a tournament title, much less a major championship. Moments later, Roddick, winner of the 2003 U.S. Open and a former No. 1, was down 5-3 in the second set.

And then, just like that, buoyed by a raucous partisan crowd, the American collected seven games in a row — and collected control of the match.

"I probably loosened up a bit," Roddick said, reflecting on the way he treated his racket.

"I just broke it a couple times — just to be thorough," he said.

Roddick has had a tough season, having lost in the third round of the Australian Open, pulled out of the French Open because of a right shoulder injury, then bowed out at Wimbledon in the second round.

He bypassed the Beijing Olympics, hoping to be better prepared for the U.S. Open by staying on this side of the world. His U.S. Open nearly ended quite early, but he credited the partisan crowd with helping.

"You guys kept me in there when I was losing my head," Roddick told the Arthur Ashe Stadium fans at match's end. "If this crowd comes with me the whole way, who knows?"