MELBOURNE, AUSTRALIA, JAN. 21 (MONDAY) -- Mats Wilander's unexpected bid to become a four-time Australian Open champion was derailed today. The former No. 1, now No. 47 after having struggled for more than two years, fell to veteran Jaime Yzaga in the fourth round.

Wilander, one of the more durable players with a 22-10 record in five-setters, faded against the hard, deep ground strokes of Yzaga, 7-5, 2-6, 6-1, 3-6, 6-1. Yzaga, ranked 86th, is the first Peruvian to reach a Grand Slam quarterfinal since the open era began in 1968.

"I'm not particularly satisfied with today," Wilander said, "but overall I'm pretty pleased."

With a fairly weak draw and a good record here -- Wilander reached the semifinals last year -- he was in the hunt for championship No. 4.

But the shots fizzled for the most part against Yzaga, who broke for the first set and took six games in a row for the third set after Wilander had tied the match at a set apiece and broken for 1-0.

"The way to beat him is to keep the pressure on him, and I didn't do that," Wilander said.

Elsewhere in the first Grand Slam event of the year, Goran Prpic, No. 56, reached the quarterfinals by beating Jan Siemerink, 7-6 (7-3), 6-7 (3-7), 6-0, 7-6 (9-7). It was a gutsy effort by both players, with Prpic playing despite a fever and a brace-encased sore knee. Siemerink had a sore shoulder that required massage and treatment by a trainer on changeovers.

On Sunday, Patrick McEnroe stepped out of older brother John's shadow and into the quarterfinals. McEnroe drove Mark Woodforde crazy with pinpoint baseline shots and canny returns in a 6-4, 6-2, 6-1 win.

There was one upset on the women's side Sunday, as No. 10 Jana Novotna defeated eighth-seeded Zina Garrison, 7-6 (7-1), 6-4. Top-seeded and three-time defending champion Steffi Graf routed Karina Habsudova, 6-0, 6-1, and No. 2 Monica Seles breezed past Catherine Tanvier, 6-2, 6-1.

Woodforde, an Australian not easily riled, drew a warning for unsportsmanlike conduct when he threw his racket twice in disgust after being broken for 0-3 in the second set. He then surged to a 4-3 lead, whacking winners all over the court. But McEnroe calmly ripped a cross-court backhand winner into the corner to hold serve for 4-4 and start a seven-game run.

The match came a year to the day after John McEnroe's blowup in the same round, a center court tantrum that led to the first expulsion for misconduct in tournament history.

Patrick, 24, came here ranked No. 114, while John, 31, a seven-time Grand Slam titlist now ranked No. 14, withdrew with a shoulder strain. If Patrick McEnroe can beat Italian longshot Cristiano Caratti, he will face Guy Forget or Boris Becker in Wednesday's semifinals.

Becker, who won a record 5-hour 11-minute match Friday, played doubles on Saturday and struggled past Wayne Ferreira on Sunday, 6-4, 7-6 (7-5), 6-4. "My legs and my mind were real tired," said Becker, trying to get past the quarterfinals here for the first time in six tries. "That was my biggest problem. Your feet boil after 2 1/2 hours."

This is McEnroe's second Grand Slam singles event -- he got knocked out of the second round at the U.S. Open in September. He's decided to concentrate on singles instead of doubles, whipping himself into shape, and it paid off with the upset of 12th-seeded Jay Berger in the third round and Sunday's win.

"He out-rallied me," Woodforde said. "I'm not saying he has better ground strokes than John. John has a lot of flair. He doesn't have the serve or the speed on court that John has. But the way he played today, maybe he could have beaten John." SEEDED PLAYERS' RESULTS Fourth Round Men

Boris Becker (2), Germany, def. Wayne Ferreira, South Africa, 6-4, 7-6 (7-5), 6-4; Guy Forget (10), France, def. Todd Woodbridge, Australia, 6-4, 3-6, 6-3, 6-4.Women

Steffi Graf (1), Germany, def. Karina Habsudova, Czechoslovakia, 6-0, 6-1; Monica Seles (2), Yugoslavia, def. Catherine Tanvier, France, 6-2, 6-1; Mary Joe Fernandez (3), Miami, def. Sabine Appelmans (16), Belgium, 6-3, 6-3; Gabriela Sabatini (4), Argentina, def. Rachel McQuillan, Australia, 6-3, 6-1; Katerina Maleeva (5), Bulgaria, def. Magdalena Maleeva, Bulgaria, 6-3, 6-2; Arantxa Sanchez Vicario (6), Spain, def. Amy Frazier (13), Rochester Hills, Mich., 6-3, 6-2; Jana Novotna (10), Czechoslovakia, def. Zina Garrison (8), Houston, 7-6 (7-1), 6-4; Anke Huber, Germany, def. Natalia Zvereva (11), Soviet Union, 6-3, 6-4. Complete Results, Page D10