ESPN Tennis

NEW YORK -- Serena Williams found herself in a time warp Friday, playing against a left-handed serve-and-volley specialist who had a game that brought back memories of Martina Navratilova, even if the talent wasn't at that level.

Williams did what she usually does when the stakes are high -- adapted and won.

The second-seeded, 11-time Grand Slam tournament champion overcame an early break in the second set to defeat Maria Jose Martinez Sanchez 6-3, 7-5 and advance to the fourth round of the U.S. Open.

Williams' sister, two-time U.S. Open champion Venus Williams, set up a fourth-round match against 2005 winner Kim Clijsters.

The No. 3-seeded Venus struggled with her serve, including seven double-faults, before pulling out a 6-2, 7-5 victory over 46th-ranked Magdalena Rybarikova of Slovakia.

Venus appeared to have some problems with her left knee. She again wore wide strips of tape above and below the joint.

She only managed to come up with 18 winners against Rybarikova, but that was enough against an opponent who made 31 unforced errors.

Clijsters beat Kirsten Flipkens 6-0, 6-2.

"I'm so excited. She's been playing so great. She was a great champion and she's still great," Venus said about Clijsters. "It's great to have her back. It's a boost for tennis and it will be a great match."

Serena's match was awkward, full of counterpunches from the game's biggest power hitter.

"I heard a guy in the crowd saying, 'Stop hitting lobs,' so I didn't hit any more lobs after that," Serena said. "My lob was not working today."

Receiving at 5-all in the first set, Serena chipped back serves, made a few passing shots and found herself at deuce for the eighth time in a game that lasted 12 minutes. Martinez Sanchez finally wore out, double-faulting twice in a row to give up the break and, essentially, the match.

This was a rematch of a third-round meeting in the French Open, which Serena won in three sets. After that match, Serena said she hit a ball she thought went off her opponent's arm and accused Martinez Sanchez of cheating by not acknowledging it.

There were no signs of animosity during their rematch on a cloudless, comfortable, 80-degree afternoon at Arthur Ashe Stadium. Serena said that episode did not motivate her, nor would she cop to having less respect for her 43rd-ranked opponent because of what happened at Roland Garros.

"I only can speak for me," she said. "I try to be very professional, extremely professional in my job. That's what I'm here to do. And win, I hope."

Serena, who came to her news conference wearing a T-shirt that said "Can't spell dynasty without nasty," lost only seven games in her first two matches. She doubled that total Friday in the kind of match that very few have to play on the women's -- or men's -- circuit these days. Serve-and-volley is out, power groundstrokes are in.

"Every time I play, I say, 'I'm going to be a serve-and-volleyer,'" she said. "I even used to like Martina Navratilova and John McEnroe. But I couldn't play more opposite than them. I love groundstrokes. I love rallies. I love hitting the ball."

Seeking her fourth U.S. Open title, Serena next meets 22nd-seeded Daniela Hantuchova, who defeated American Vania King 6-2, 6-2.

Clijsters left tennis in 2007, got married and had a child. But she returned to the tour this month and will enter the rankings after the tournament.

Clijsters had 13 winners and finished off Flipkens in 62 minutes.

Clijsters said she didn't plan to focus on Venus' knee too much.

"When you play against her, you know that the balls are coming fast," the Belgian said. "You don't really have time to worry too much about injuries or anything."

Venus and Clijsters have met 10 times, with the American holding a 6-4 edge. Their last meeting came in the 2005 U.S. Open, and Clijsters beat Williams in the quarterfinals on the way to the championship.

"It's been so long [since] I stood in front of someone like her, who can play as well as she can," said Clijsters. "I know what kind of tennis I have to bring."

Tenth-seeded Flavia Pennetta also moved on Friday, defeating Aleksandra Wozniak of Canada 6-1, 6-1. No. 8 Victoria Azarenka of Belarus fell to No. 26 Francesca Schiavone of Italy 4-6, 6-2, 6-2.

Information from The Associated Press and Reuters was used in this report.