NEW YORK, NOV. 20 -- Second-seeded Martina Navratilova was upset by sixth-seeded Gabriela Sabatini. 6-4, 7-5, tonight in the quarterfinals of the Virginia Slims tennis championships, ending Navratilova's bid for a fifth straight title.

"Nothing was working right," Navratilova said. "Nothing was there. I don't know what is was. It might have just been nerves. Everything was off. She sort of shocked me."

"I knew I could win this match," Sabatini, 17, said. "Today everything worked perfectly. I think I played great today, one of the best matches I've ever played."

Sabatini will meet eighth-seeded Manuela Maleeva of Bulgaria, who upset No. 4 Pam Shriver, 6-2, 3-6, 7-5, earlier. In Saturday's other semifinal, top-seeded Steffi Graf plays fellow West German Sylvia Hanika.

Sabatini had beaten Navratilova once in eight matches, in the semifinals of the 1987 Italian Open.

Sabatini broke Navratilova's serve to go up, 4-3, in the first set, then held twice to win the set.

After breaking each other twice in the second set, Navratilova and Sabatini were tied, 5-5. Sabatini broke Navratilova again in the 11th game and then held serve to win the match as Navratilova made four backhand errors in the final game.

In the third set of the Maleeva-Shriver match, there were nine service breaks, including seven in a row to start the set. "The third set was crazy," said Maleeva. "We were both returning very well."

Shriver had a 5-3 lead in the final set, but Maleeva rallied to win the last four games and beat Shriver for the first time in six meetings.

"I didn't serve that well," Shriver said. "I kept thinking I would get into my serve, but it didn't answer. Nobody was home."