There won't be a Wimbledon showdown between the Williams sisters after all.

Serena retired from her third-round match with unheralded Virginia Ruano-Pascual on Monday, hobbling with a leg injury and trailing 7-5, 4-1."I could have carried on if I wanted, but I have to think about the future," she said. "I don't want to hurt myself over something silly and be out for maybe two months just because I didn't stop."

Serena, 16, had easily won her first two matches and was heavily favored to beat Ruano-Pascual and set up a fourth-round encounter against 18-year-old sister Venus, who was playing Chanda Rubin on Monday.

A Williams meeting would have been their third this year and Wimbledon's first match between sisters since Gail and Carol Sherriff of Australia played in 1966.

"We were going to be pretty excited about facing each other again," Serena said. "It was going to give something exciting for Eng-land for once."

Serena, playing her first Wimbledon and third Grand Slam, declared that she had been on course to win the title.

"I had all the expectations for this Wimbledon," she said. "I expected to go all the way. I guess I just won't be able to this year. . . . In the future, I definitely see myself as one of the champions."

Serena said Venus, who is seeded No. 6, could be a champion this year.

"She might go a long way now that I'm out of the draw," she said. "I'll give her a couple of tips."

Serena fell behind right away and never recovered against the 47th-ranked Spaniard. At 4-5 in the first set, Williams took a three-minute injury timeout while a trainer sprayed and strapped her left calf.

Williams said she injured herself while slipping on the slick grass during the middle of the set.

Williams broke in the next game for 5-5, but Ruano-Pascual won the next two games at love to take the set and ran off the first four games of the second.

Williams was clearly slowed by the injury, favoring her left leg and failing to run after some shots.

After winning the fifth game of the second set, Williams walked over to the chair umpire and announced she could not continue. She packed her bag quickly and left the court as her mother Oracene, sitting in a wheelchair with a broken ankle sustained two weeks ago, watched solemnly.

"Early in the match, (the injury) wasn't getting any worse, and I thought I can keep going," Williams said. "But when I saw it wasn't getting any better, I figured it was time to stop play."

Serena Williams neglected to shake hands with her opponent, describing it as oversight because she had never retired during a match before. She paid little credit to Ruano-Pascual.

"She had a pretty good today, but if I was in better shape, it wouldn't have been happening at all," Williams said.

Ruano-Pascual seemed stunned at her victory. As she sat in her chair, she shrugged and flashed an embarrassed grin.

Williams also pulled out of the women's doubles, in which she was paired with her sister but said she may still play in the mixed doubles.

"I think (the injury) will clear up in a short time," she said. "It's not hurting as bad as it was on the court. It's already feeling a little better."

On another rainy day at Wimbledon, French Open champion and No. 5 seed Arantxa Sanchez Vicario moved into the fourth round with a 7-5, 6-2 win over Sylvia Plischke.

In early men's play, Todd Martin completed a rain-delayed third round match against Todd Woodbridge, winning 6-4, 4-6, 7-6 (7-1) 6-4.

Martin is the only American man left in the tournament other than defending champion Pete Sampras, who was resuming his third-round match against Thomas Enqvist.

In the day's featured Centre Court match, No. 6 Patrick Rafter, the reigning U.S. Open champion, was to face No. 12 Tim Henman of Britain for a place in the quarterfinals.

The second week started under cloudy skies, and play was suspended by rain in early afternoon.

Four days of play were delayed by rain last week, leaving the tournament 13 matches behind schedule, but officials kept with tradition and permitted no play Sunday.