NEW YORK, SEPT. 5 -- Zina Garrison had a bad ankle, Jana Novotna had a bad day and today's two U.S. Open women's quarterfinals were disappointingly one-sided. Top-seeded Steffi Graf trailed briefly in the first set before she flattened 12th-seeded Novotna, 6-3, 6-1. No. 6 Arantxa Sanchez Vicario of Spain took advantage of fourth-seeded Garrison's injury for a 6-2, 6-2 victory at the National Tennis Center.

Garrison was rendered lame and cautious by an aggravated Achilles' tendon and considered withdrawing during the first set. After undergoing intensive treatment Tuesday, she took the court this afternoon in the hope that 18-year-old former French Open champion Sanchez Vicario would somehow hand her their match.

But she was unrelenting, moving Garrison painfully around the court and bringing her to tears. Garrison hobbled to 35 unforced errors, and wept on the changeover after her serve was broken to open the second set. Sanchez Vicario thus reached the semifinals here for the first time, and denied Garrison a rematch with Graf, whom she had so stunningly upset in the Wimbledon semifinals.

"I just wanted to stay out there and finish," Garrison said. "I wanted to at least make her work for the money she was getting in the next round."

Graf, the defending champion, has been disturbingly inconsistent this season, her only Grand Slam title coming at the Australian Open. She arrived here intent on reestablishing her pattern of dominance, but her match against serve-and-volleyer Novotna did not begin convincingly. She trailed by 0-2 in the first and was in grave danger of 0-3, facing a break point.

That, however, was the last time Novotna made the slightest impression on the West German, who promptly delivered a service winner. Graf swept the next four games, including the first two at love. She made just one unforced error in the second set, and broke Novotna six times in eight service games. With that easy passage into the semifinals, in which she will meet Sanchez Vicario, she is poised for her third straight U.S. Open title.

"I'm in the perfect position," Graf said.

She still is vaguely dissatisfied with her form, which has suffered from nagging poor health and a rash of European tabloid stories concerning her family life. "I didn't have the best start today, that's for sure," she said. But Novotna said, "I think no one can stop her from winning this championship now."

The other semifinal pits fifth-seeded Gabriela Sabatini against No. 8 Mary Joe Fernandez, who have split 10 meetings. Neither has beaten Graf this year, and although Sanchez Vicario has a precedent with her upset of Graf in the 1989 French Open final, she has not beaten her since.

If Garrison seemed overly distraught by her loss, it was because her injury ruined an opportunity. She was perhaps the last player left who could face Graf with something like confidence, off her three-set victory at Wimbledon. Instead Garrison became only the latest seed to be upset: No. 2 Martina Navratilova was forced out in the fourth round by Manuela Maleeva-Fragniere, No. 3 Monica Seles was gone by the third at the hands of obscure Linda Ferrando.

"It happens," Graf said. "They had days that were not their best."

Sanchez Vicario denies she had any knowledge of Garrison's injury, preferring to think she had beaten her on skill. "I think I play really well, move the ball around, pressure her all the time," she said. But Garrison was clearly inhibited by the injury, which denied her two crucial assets: speed and volleying. It was an indication of how off she was that she and Sanchez Vicario had met twice before, splitting three-setters.

Garrison had her normally unassailable serve broken six times and trailed by 0-3 in each set as she waited at the baseline, trying to hang on. "I really wasn't here," Garrison said. "I was pushing the ball back, hoping she'd miss. You try to play it out mentally."

Garrison tried to tighten the match when she broke the increasingly confident Sanchez Vicario in the fourth game of the second set to close to 3-1. But the teenager got another break for an insurmountable 5-2 lead on a freakish point. As Garrison served at 15-40, Sanchez Vicario charged the net and made a low backhand volley that caught the net cord and trickled over.

"It was a little lucky," Sanchez Vicario said. "But it was an important point, because it makes it 5-2 instead of 4-3 and next time I am serving for the match."

Garrison ended the match with three straight unforced errors, the last a weak forehand service return into the net. It was the first time in two years she failed to make the Open semifinals, in 1988 upsetting Navratilova in the quarterfinals and last year ending Chris Evert's career at the same stage of the tournament.

"It's pretty disappointing," she said. "I really felt I had an opportunity here. But that's the way things fall. I've just got to get it fixed."

Garrison later withdrew from the doubles. She and Patty Fendick, seeded No. 7, were to meet the No. 14 Natalia Medvedeva and Leila Meskhi in the fourth round.