MELBOURNE, AUSTRALIA, JAN. 22 (TUESDAY) -- The Steffi Graf era at the Australian Open is over.

Jana Novotna, a Czechoslovakian who revamped her game, defeated Graf, 5-7, 6-4, 8-6, today to end the German's three-year, 25-match reign at this Grand Slam event.

"I beat the number one player. It feels like the end of the tournament," said Novotna, appearing physically and emotionally drained.

The 10th-seeded Novotna advanced to the semifinals, as did Monica Seles, who defeated Anke Huber, 6-3, 6-1. Seles will play Mary Joe Fernandez, a 6-3, 6-2 winner over Katerina Maleeva, in the semifinals. In the men's tournament, Stefan Edberg and Ivan Lendl moved closer to a semifinal showdown, reaching the quarterfinals by getting by Jim Courier (4-6, 6-0, 6-4, 5-7, 6-2) and Aaron Krickstein (6-2, 6-2, 6-1), respectively.

In a brilliant match that featured a relentless net attack by Novotna and a desperate fight by Graf, Novotna put away the victory at love in the final game after double-faulting at break point on her previous service.

"I was better and more consistent at the net than ever," said Novotna, who lost all nine of her previous matches against Graf. "I was more aggressive. I didn't try to beat Steffi from the back. There are weaknesses in Steffi's passing shots, and I never really choked at the net. That put pressure on Steffi because she knew I wasn't making any mistakes at the net. So she had to be perfect."

Graf, the three-time defending women's champion and top seed, had not lost in the quarterfinals of a Grand Slam event since the 1986 French Open. She had not lost in the Australian since the third round in 1984 -- she skipped the '85 and '87 tournaments and the Australian wasn't played in 1986 -- and had never lost in this stadium's center court.

"She can play from the baseline, or come in," Graf said. "She mixes it up. You never really know what to expect. . . . I chose the wrong tactics to come in too much today. I just have to play better."

Graf had dropped only 11 games in her first four matches. But against Novotna, who beat No. 8 Zina Garrison in the fourth round, she looked a step slower and mistake-prone, slapping easy ground strokes into the net. Novotna fought off two break points in the second set before taking it on her first opportunity when Graf poked a forehand crosscourt volley wide.

Novotna blew her first chance at victory when she double-faulted at break point in the next game, but broke back on her fifth break point against Graf in the 13th game.

This time, Novotna didn't yield at all, and Graf had nothing left. Novotna won at love when Graf weakly hit a backhand return into the net.

"This morning I felt great in practice, but in this match I didn't play well at all," Graf said. "Today she stuck in and pushed herself and didn't make the mistakes she sometimes does. She's playing more with her head, using the right strokes when she needs them."

In their own fashions, Lendl, the two-time defending Australian Open champion, and Edberg, the two-time former champion, reached the quarterfinals. Lendl played his best match of the tournament in beating Krickstein.

"When I play Aaron, I feel about it this way: Whatever we start doing on the court, I'm at least as good as he is at it or a little better," said Lendl, who has beaten Krickstein in six of seven matches. "So something unusual would have to happen for me to lose the match."

Krickstein has slipped from No. 8 two years ago to No. 22. He had his only big moment in the first game of the match, when his serve flicked off the edge of Lendl's racket, bending it. Lendl cracked the racket over his knee, tossed it away, picked up another, and won 10 of the next 11 games.

Edberg played less perfectly and got a stiffer challenge from Courier. Edberg uncharacteristically double-faulted on set point in the opener, then asserted himself in the second set by coming to the net faster and driving his serves deeper. He won nine of 10 games until he had a 3-1 lead in the third set. But Courier's deep and awkward but punchy baseline shots began to force Edberg away from the net.

Courier drew a warning for an obscenity -- actually a string of curses that cost him a $2,000 fine -- when he double-faulted, giving Edberg a break point in the first game of the fourth set. Courier responded by winning the next three points to hold service, then took the set to even the match.

In the final set, Edberg's experience and stamina paid off.

"I could bring out that little extra in the fifth set, which is necessary to win a five-setter," Edberg said. "It's all got to do with confidence."

Edberg plays No. 86 Jaime Yzaga, the first Peruvian to reach the quarterfinals of the Australian since the start of the open era in 1968. Yzaga beat three-time former champion Mats Wilander, who has dropped to No. 47, 7-5, 2-6, 6-1, 3-6, 6-1. SEEDED PLAYERS' RESULTS Men's Fourth Round

Stefan Edberg (1), Sweden, def. Jim Courier (16), Dade City, Fla., 4-6, 6-0, 6-4, 5-7, 6-2; Ivan Lendl (3), Greenwich, Conn., def. Aaron Krickstein (13), Grosse Pointe, Mich., 6-2, 6-2, 6-1.Women's Quaterfinals

Mary Joe Fernandez (3), Miami, def. Katerina Maleeva (5), Bulgaria, 6-3, 6-2; Jana Novotna (10), Czechoslovakia, def. Steffi Graf (1), Germany, 5-7, 6-4, 8-6.