U.S. Open: Williams sisters advance to 4th round

NEW YORK — Following her victory Friday, defending U.S. Open women's singles champion Serena Williams switched into a yellow T-shirt with this bit of wisdom in blue script: "Can't spell dynasty without nasty."

Williams' brand of tennis is plenty nasty, particularly at Grand Slam tournaments. By beating serve-and-volleying Spaniard Maria Jose Martinez Sanchez 6-3, 7-5 on Friday, Williams improved to 28-1 over the past five majors.

The secret to her success?

"You can never underestimate anyone. Some people, some days, they have great days," said the No. 2-seeded Williams, whose sister Venus also won Friday. "I just go and look at every opponent as the best player in the world."

Perhaps some of her colleagues should take that approach, as well.

This has been a topsy-turvy U.S. Open for the women: No. 8 Victoria Azarenka's 4-6, 6-2, 6-2 loss to No. 26 Francesca Schiavone on Friday came a day after No. 4 Elena Dementieva and No. 5 Jelena Jankovic were upset. All told, 11 of the 20 highest-seeded women are gone, and the third round is only halfway done.

"Now there is not a lot of difference between players," Sanchez Martinez said. "I think anyone can win any match."

No. 3 Venus Williams, the 2000-01 Open champion, avoided adding to the list of stunning results when she got past 46th-ranked Magdalena Rybarikova of Slovakia 6-2, 7-5. Next up for the elder Williams: a fourth-round match against Kim Clijsters, who recently came out of retirement and is playing in the tournament for the first time since winning it in 2005.

"She was a great champion," Venus Williams said. "She still is."

No. 1 Dinara Safina made it to today's third round, but barely. She needed more than 41/2 hours to get through two three-set victories.

"Nothing's a given. Everyone comes out, they play well — if you aren't the better player that day, you're going home. That's just how it is," Venus Williams said. "There is depth on the women's tour, definitely."

The best men have faced no such problems: No. 3 Rafael Nadal's 6-0, 3-6, 6-3, 6-4 victory Friday night in the last match of Day 5 means the men seeded 1-16 all reached the third round at a Grand Slam tournament for the first time in the 41-year Open era.

"There is a gap," said Jurgen Melzer, who lost to No. 6 Juan Martin del Potro 7-6 (6), 6-3, 6-3.