The didn't like the court today, she didn't like it that her opponent was left-handed, she didn't like this and she didn't like that. Mostly, Pam Shriver didn't like herself.

So she lost at Wimbledon. "It's predictable," she said. "I don't deserve any better."

Seeded seventh and given a serve-and-volleyer's chance to win the whole thing, the teen-ager from the Baltimore suburbs lost her first two service games and disintegrated under the big-serve pressure of 10th-seeded Barbara Potter, 6-2, 6-4.

On a day when Chris Evert Lloyd knew she couldn't lose, Shriver knew she couldn't win.

"I need to work," said Shriver, the tour's youngest veteran, to be 20 this Sunday but in her fourth year on the road. "And I just don't . . . I'll get sick of losing to people like Potter . . . She works four or five times harder than me, which doesn't say much for me. If I had a little bit of her attitude, I would do better myself . . . Otherwise, I'll be ranked somewhere from seven to 15 all my life."

Evert, who said she "never thought about defeat," lost the first set to Virginia Ruzici before "lifting the level of my game" for a 6-7, 6-3, 6-1 victory that was her 22nd in a row over eight years against the Romanian.

Among those also advancing to the quarterfinals were top-seeded Martina Navratilova and her next opponent, unseeded JoAnne Russell (who upset No. 9 Sylvia Hanika to win her fourth straight three-setter).

Also, six-time champion Billie Jean King moved along with Tracy Austin (next for BJK) and Anne Smith, a surprise winner today over fourth-seeded Andrea Jaeger, who served atrociously and blamed her misfiring ground strokes on a lack of practice in these rainy days in Londontown.

Mats Wilander, 17, the French Open champion who is one of the rare candles in the darkness of the men's side, won a third time by beating Stanislov Birner, 6-3, 6-4, 6-4. Now the seventh-seeded Borg clone will face veteran Brian Teacher, 11th seed here.

Third-seeded Vitas Gerulaitis and No. 14 Roscoe Tanner needed five sets to advance to a fourth-round meeting. Gerulaitis won three straight sets from Tomas Smid, while Tanner beat Vijay Amritraj after blowing a two-set lead, 6-4, 6-4, 4-6, 4-6, 6-3. Johan Kriek (No. 5), Gene Mayer (6), Mark Edmondson (12) and Buster Mottram (15) had easier times against undistinguished opponents.

For Shriver, nothing was easy today. Once thought of as a gifted prodigy when, at 16, she lost the U.S. Open final to Evert, she now is a gangly prospect on a treadmill going nowhere. For a year, she would confess, she hasn't worked the way the very best players do. Only Saturday, for instance, she ran sprints with Navratilova for 15 minutes.

"On Monday, I was still sore," Shriver said dispassionately. "If I can't run sprints for 15 minutes without getting sore . . . That's the kind of shape I'm in."

It's not much better mentally. "As a kid, I thought I was pretty hot stuff," she said. "I took it for granted . . . Potter came in with a positive attitude today, and I was a bit apprehensive."

Shriver didn't like playing on court 12, out in the Wimbledon boondocks, because "I play better when more see, whereas she gets up-tight."

Not only was Shriver intimidated by Potter's attitude, not only did the assignment of courts reveal her grasping for straws of assistance, she said Potter's left-handedness makes a big difference. "That left-handed serve is worth probably two, three points a game," she groaned.

Even as Shriver was losing, for a half-hour or so this afternoon the possibility of a tournament without Navratilova or Evert reared its homely head.

A teen-ager from Houston, Zina Garrison, ran off to a 3-1 lead over Navratilova on Centre Court before the 1978-79 champion discovered an exploitable weakness on the forehand side.

Mercilessly, Navratilova's serve, perhaps the strongest accurate delivery in the women's game, pounded at Garrison's flaw. After her first match in the past four rainy days here, Navratilova patted the Texan's shoulder kindly. Nothing personal, Zina, just business.

"If a tough match presents itself, I feel ready," said Navratilova, who has lost only 16 games in three straight-set victories here. Then the woman with a 51-1 record this year (she has won 13 of her last 18 tournaments, never losing before the final) cooly added, "I hope not to be tested."

More and more, it appears that only Evert can hope to test Navratilova. And Evert today gave small sign of the necessary strength to handle Navratilova's powerful serve-and-volley game. As long as Ruzici was aggressive and following her heavy shots to the net, the Romanian had Evert on the run.

"Then I started hitting out more, and she got tight," Evert said. "She's always able to play one good set against me, but not two. I never thought about defeat at all. I knew I'd been in that position with her before. I thought I could guts it out."

By moving Ruzici from sideline to sideline, Lloyd not only wore her out physically but mentally. The explosive hisses coming from Ruzici on each shot--a sibilant grunt, if you will--came to be puffs of exhaustion, a death rattle.

"She was very mentally tired," said Evert, who has beaten a hundred women the same metronomic way.

King, reaching the quarterfinals for the 19th time in 19 tries, said her victim today, sixth seed Wendy Turnbull, "never got started." King played raggedly, happy only with her trusty backhand, and says she now faces "a good challenge" against Austin, the indefatigable base liner who is 5-0 lifetime against King. .

After two straight three-set victories, Gerulaitis was extended by Smid. "I wasn't serving well in the first two sets and couldn't find any rhythm at that point," said Gerulaitis, who never has reached the final of any major championship outside the Australian Open.

"I said to myself, 'I don't mind losing, but I have to make a fight of it.' "