Since she arrived in England last week, two-time Wimbledon champion Serena Williams had been operating on the conviction that her will to win was strong enough to overpower the combined talent, skills, hard work and desire of whatever opponent she faced.

And through her first two matches Williams was vindicated, pulling out victories -- albeit sloppy ones -- that propelled her one step closer to a much anticipated fourth-round meeting with elder sister Venus and to a women's final that she repeatedly referred to as her "destiny."

Williams's fanciful theory slammed headlong into reality Saturday in the unlikely form of 30-year-old Jill Craybas, the world's 85th-ranked player, who sent Williams packing from the tournament she once ruled, 6-3, 7-6 (7-4). It was the fourth-ranked Williams's earliest Wimbledon defeat since she made her debut in 1998.

Though the loss reduced her to tears and caused her to interrupt her post-match interview several times to dab her eyes with a tissue, Williams -- who refused to use her injured left ankle as an excuse -- needed only to look in a mirror to find the cause.

Craybas surely did her part in notching the biggest victory of her career, landing 66 percent of her first serves, handling the pace of Williams's vaunted groundstrokes and, most importantly, keeping her composure as Williams ratcheted up her power, as well as her grunts and glares, in a vain attempt to force a third set.

But in the end, Williams's role in the outcome was larger than that of Craybas.

"I'm just used to winning these kind of matches," Williams said afterward. "It's just hard when you go out there and you can't make a shot, and you've been making them for years. It's like -- it's a battle."

Part of the reason for Williams's ineffectiveness is that female tennis pros are more fit and strong than even five years ago, working harder in the gym and investing more power in their games. The other part is that Williams hasn't kept up. And steely resolve simply isn't enough to brook the difference.

Faced with the most embarrassing loss of her career, Williams uttered the critical words Saturday that suggest she may be ready to set her acting bug aside and rededicate herself to the sport that made her famous.

"I definitely think it's important for me to practice harder than what I've been practicing," Williams said. "I've never been big on practicing. I've kind of been all about playing."

If the outcome was a wake-up call to Williams, it was the sweetest possible reward for Craybas, who nearly quit the tour after hitting a competitive plateau a few years back. The top junior in Rhode Island as a teenager, Craybas is among the tiny fraction of players who deferred turning pro until after getting a college diploma. Along with her telecommunications degree, she also earned an NCAA tennis title while a student at the University of Florida.

But her fortunes as a pro, while better than most, haven't been world caliber. In nine years on the tour, Craybas has won one singles title (the 2002 Japan Open) and risen no higher than 51st in the rankings (January 2003). And in two previous meetings with Serena Williams, she had never won more than three games in a set.

While Saturday's victory was "absolutely fantastic," Craybas said, it meant even more because of the work she and her coach had devoted these last months to the mental aspect of her game. At 5 feet 3 and 123 pounds, Craybas has logged long hours in the gym in order to compete with bigger, stronger players. But until recently, her mind-set had held her back.

"The two previous meetings when I played [Williams], I don't think I believed that I could actually win the match -- no matter how well I was playing," Craybas said. "Even if you're playing great, if you don't believe it, then it usually doesn't happen."

When she walked on the court Saturday, Craybas felt she was Williams's equal.

The match had been scheduled for Center Court. But it was moved to Court No. 2, which seats fewer than 3,000 people and is known as the "Graveyard of Champions," once it became clear that Center Court's previous match, between David Nalbandian of Argentina and Scottish teenager Andrew Murray, was headed to five sets.

Williams was erratic from the outset, falling behind 2-4 as she sprayed first serves and groundstrokes all over the place. She was also breathing heavily after only a few games, as she had in previous matches. In 42 minutes, she was down one set, the sky was darkening and rain threatened.

Williams changed tactics in the second set, shaving pace off her serves in the interest of getting one in. The change-up won her a few points, and she reeled off three consecutive games to take a 5-4 lead. At times, she moved as if every step pained her. Other times, she ran down drop shots and wailed at her strokes as if she had power to spare.

But Craybas hung in to force a tiebreaker in which Williams committed the errors that cost her the match.

SERENA WILLIAMS

Jill Craybas, ranked 85th in the world, celebrates after her 6-3, 7-6 (7-4) win over Serena Williams. Craybas described the victory as "absolutely fantastic."