V. Williams, Roddick remain perfect

WIMBLEDON, England -- Venus Williams is back in a Grand Slam groove.

She's pounding serves, dictating points, not letting opponents into the match.

And now the two-time Wimbledon champion gets a chance to inflict her good form on the player responsible for Williams' surprising exit at the last major.

Williams picked up a third consecutive lopsided victory, outclassing French Open semifinalist Nadia Petrova 6-1, 6-2 Friday to reach the round of 16 at the All England Club for the sixth year in a row.

Williams next faces another Russian, Vera Zvonareva, who beat her in the fourth round at Roland Garros -- Williams' earliest loss at a Slam in two years. The American couldn't prepare properly for that event because of an abdominal injury.

"There's no excuses for me. I have to perform. If I have a bad day, it's a bad day," the fourth-seeded Williams said, "but I come back stronger."

Andy Roddick is looking rather dominant himself, also not dropping a set yet. He reached Wimbledon's fourth round for the first time by beating No. 25 Tommy Robredo 7-6 (5), 6-4, 6-4.

Roddick didn't lose his serve once and is playing the sort of confident tennis that could very well bring him his first Grand Slam title. His last two wins came on Centre Court, and he looks quite comfortable in the setting, even if he says otherwise.

"I don't think it can be natural at any time. It's a very special place. I don't think it's ever going to lose that aura," Roddick said. "Obviously, I'm getting more and more used to it. But there are always some jitters early on in a match, for sure."

He compiled nine aces and 33 service winners, facing just one break point.

Roddick's opponent for a quarterfinal spot is No. 12 Paradorn Srichaphan, who upset Andre Agassi a year ago. Paradorn defeated 17-year-old Spaniard Rafael Nadal, who was trying to become the youngest man in the fourth round since Bjorn Borg in 1973.

No. 4 Roger Federer, No. 8 Sjeng Schalken and Australian Open runner-up Rainer Schuettler also won. Schuettler had the most work to do, overcoming Todd Martin 4-6, 7-5, 6-7 (1), 6-1, 7-5 in Martin's record-tying 14th five-setter at Wimbledon.

Ivo Karlovic -- the 6-foot-10 qualifier who stunned defending champion Lleyton Hewitt -- bowed out with a 7-6 (5), 3-6, 6-3, 7-6 (4) loss to 6-foot-5 Max Mirnyi despite slamming 26 aces.

Women's matches went to form, too, with one exception: No. 7 Chanda Rubin was beaten 7-6 (6), 6-3 by Silvia Farina Elia, never a quarterfinalist in 43 majors.

No. 2 Kim Clijsters and 1999 champion Lindsay Davenport won in straight sets. So did No. 16 Zvonareva, who can expect a tougher time against Williams.