NEW YORK — If anyone still harbored any doubts about whether Serena Williams is back at her best, she put on a pretty persuasive performance during the first 17 minutes of her third-round match Saturday at the U.S. Open.
That's how long Williams needed to build a 5-0 lead en route to a 6-1, 7-6 (5) victory at Flushing Meadows over one of the best players the women's field had to offer: fourth-seeded Victoria Azarenka, a Wimbledon semifinalist two months ago.
Listen to Azarenka describe how it felt to stand across the net from Williams during her superb start:
"What's it like? It's painful," said Azarenka, who won eight points in those opening five games. "To have somebody just going at you like that, it's a little bit painful."
Eventually, though, Azarenka straightened her own play out enough to make things interesting in the second set. She erased four match points, broke when Williams served for the match at 5-3, and left Williams saying she wasn't pleased.
"She won the first set very easily, and it was a little bit too easy, so then she got tested — and she needed to be tested," said Williams' mother, Oracene Price.
Williams passed the test, and showed off her fitness, which is much improved from when she lost in the fourth round at Wimbledon. At the end of one point, she did the splits. On another, she raced all the way over to the blue sign near the stands to smack a forehand winner.
She and Azarenka described the level of play as being worthy of a Grand Slam semifinal, rather than the Week 1 matchup that it was. But they wound up being drawn to meet this early because Williams is seeded only 28th, a reflection of her lower-than-usual ranking as a result of nearly a year's absence from the tour because of a series of health scares.
The 29-year-old American already owns 13 major championships, including three at the U.S. Open, which is why, when she was asked how she can play so well now, Williams replied: "I mean, I was a pretty good player before. So just trying to get back into that rhythm and feel it again."
In the fourth round, Williams will face former No. 1 Ana Ivanovic of Serbia, the 2008 French Open champion, who is seeded 16th.
"It's exciting, at least for me. I think she's the hottest player out there at the moment. She's been playing so well lately. It is going to be a good challenge," Ivanovic said after ending Sloane Stephens' surprising run by beating the 18-year-old American 6-3, 6-4 in Arthur Ashe Stadium on Saturday night.
Ivanovic acknowledged that Williams will be the "favorite, that's for sure" but also said: "I know I can give her a tough match. She beat me in the past, but maybe I can go for revenge on Monday."
Her victory over Stephens was followed Saturday by top-seeded Novak Djokovic against two-time U.S. Open semifinalist Nikolay Davydenko.
The woman who's seeded No. 1, Caroline Wozniacki, eliminated Vania King of the United States 6-2, 6-4, and will continue her bid for a first Grand Slam title against 15th-seeded Svetlana Kuznetsova, owner of two major trophies.
Also into the fourth round with victories Saturday were 2010 French Open champion Francesca Schiavone of Italy, who got past Chanelle Scheepers of South Africa 5-7, 7-6 (5), 6-3; No. 17 Anastasia Pavlyuchenkova of Russia, who beat 2008 U.S. Open runner-up Jelena Jankovic of Serbia 6-4, 6-4; and No. 10 Andrea Petkovic of Germany, who defeated No. 18 Roberta Vinci of Italy 6-4, 6-0 to reach the fourth round at Flushing Meadows for the second year in a row.
"Grand Slams are very stressful," Petkovic observed. "I think any player that you ask — and if he answers honestly — it's a lot of stress."
That, as much as anything, could explain why so many players have been quitting during matches because of injury or illness: No. 9 Tomas Berdych (shoulder) and No. 31 Marcel Granollers (abdominal muscle) did so Saturday, raising the total retirements in men's and women's singles to a record 14 by the third round.
Never before had more than 12 players stopped during a match throughout the course of any entire Grand Slam tournament in the Open era.
"For me, it is shocking to see so many retirements. I have never retired in my whole life, except once when I played against (James) Blake in Paris, but I didn't even walk onto the court. For me it doesn't matter how bad I'm feeling, I will be out there and giving it a try, because you never know what's gonna happen," 16-time major champion Roger Federer said.
"Look, every player feels different," he added. "It's unfortunate it happens."
Federer moved into the fourth round for the 30th consecutive Grand Slam tournament by overcoming what he called "tricky wind" and a second-set blip to defeat No. 27 Marin Cilic of Croatia 6-3, 4-6, 6-4, 6-2.
