NEW YORK (AP) – Hardly at her best, barely beating one of the tour’s pesky teens, Serena Williams suddenly found herself face-down at the U.S. Open.

Running for a ball she couldn’t reach, the six-time Grand Slam champion slipped and planted both palms on court to brace herself. Williams shook the sting out of her hands, beckoned a ball boy to retrieve her fallen racket, then took her sweet time before facing break point. Recomposed, Williams smacked a service winner at 111 mph, an ace just as fast, and forced an error. Just like that, she held serve en route to beating 30th-seeded Tatiana Golovin 7-5, 6-4 Friday night to reach the Open’s fourth round.

“I was playing two opponents: her and myself,” Williams said.

She made it through, though, as did all the favored women Friday, including No. 2 Amelie Mauresmo, No. 6 Elena Dementieva, No. 8 Jennifer Capriati, No. 10 Vera Zvonareva, No. 15 Patty Schnyder, and No. 16 Francesca Schiavone, who ended wild card Angela Haynes’ run 6-3, 7-6 (3).

It wasn’t that way among the men, though.

No. 7 Juan Carlos Ferrero (the 2003 runner-up), No. 8 David Nalbandian (a semifinalist last year) and No. 12 Sebastien Grosjean all lost. And No. 23 Vince Spadea’s 6-3, 4-6, 3-6, 6-3, 6-4 defeat against Austria’s Jurgen Melzer left just two of the 18 U.S. entrants still in the draw.

Stefan Koubek, got past Ferrero 7-6 (2), 4-6, 6-7 (6), 6-2, 6-3. Nalbandian was a 6-7 (4), 6-4, 7-5, 2-6, 6-4 loser against Mikhail Youzhny, and Grosjean was beaten 6-4, 6-4, 1-6, 6-1 by Tommy Haas, once ranked No. 2 but out all of last season because of two right shoulder operations.

Williams missed 8 months after left knee surgery on Aug. 1, 2003, including skipping a title defense at last year’s U.S. Open. She’s won just one tournament since returning.

One good sign Friday: The knee held up well. On one point, she ran up to get a drop shot, lost her footing, and did the splits near the net. After making sure her forehand landed in, Williams rose and laughed at her pratfall.

Asked about her knee, Williams offered this assessment: “It’s holding up. I don’t make excuses.”

Now she will face Schnyder, a Swiss left-hander who saved three match points and eliminated Daniela Hantuchova 6-4, 4-6, 7-6 (6).

Unlike when she was challenged in the Wimbledon final, Williams was able to find a solution, in part by being more patient on points. It helped, too, that Golovin wasn’t as cool as Sharapova, even double-faulting three times in a game to get broken to 4-1 in the second set.

Still, Golovin put up much more of a battle than she did in a 6-2, 6-1 fourth-round loss to Williams at the All England Club,

“Obviously, I’m pretty happy, because I played her better than I did at Wimbledon,” Golovin said. “I was ready for what she was going to do, so I can’t say that I was impressed.”

Like Williams, Capriati used to be ranked No. 1. And Capriati has won majors – three, all told. Her opponent Friday, Vera Douchevina, is ranked 88th and has won three matches at majors.

But Capriati had lapses is a tougher-than-expected 6-0, 6-7 (4), 6-3 win against the 17-year-old Russian.

And a pattern is developing: Both Williams sisters have faced challenges; No. 4 Anastasia Myskina, the French Open champion, lost to a Russian teen Thursday; Sharapova was extended to three sets in both her matches at the Open; defending champ Justine Henin-Hardenne dropped a set against a qualifier; and Mauresmo had to overcome a set deficit in the second round.

Showing little of the rust or fatigue she displayed in that match, Mauresmo did beat No. 31 Maria Vento-Kabchi of Venezuela 6-2, 6-0 to reach the fourth round.

“It was much better than the match I had to play two days ago,” Mauresmo said. “I felt much more comfortable on the court. My serves, my groundstrokes – everything was coming together.”

Williams probably wishes she could say the same.

AP-ES-09-03-04 2234EDT