Ivan Lendl destroyed John McEnroe's title dream with a straight-set victory today in the quarterfinals of the $2.4 million Australian Open tennis championship.

"I played very well, but he played better," McEnroe said.Lendl crashed a remarkable 40 passing shots past the American to win 7-6 (7-0), 6-2, 7-6 (7-2) and earn a meeting in the semifinals with 11th-seeded Thomas Muster of Austria.

Muster gained the semis for the first time in a Grand Slam event when two-time champion Stefan Edberg of Sweden was forced to default with a mysterious and painful back injury.

Edberg suffered the injury during his fourth-round victory over Australian Pat Cash and said it would keep him out of action for at least two weeks.

Miloslav Mecir of Czechoslovakia, the ninth seed, crushed Yugoslav teen-ager Goran Ivanisevic 7-5, 6-0, 6-3 to also advance to the semifinals, where he will face unseeded Swede Jan Gunnars-son.

Gunnarsson, who almost retired a year ago after a painful knee injury and is playing in the event for the first time, beat his 14th-seeded compatriot Jonas B. Svensson 6-0, 6-3, 4-6, 6-4.

Both men's semifinals are scheduled for Friday.

Lendl, who has never won the Australian Open, was at his very best against McEnroe, whose last victory in a Grand Slam tournament was in the 1984 U.S. Open.

McEnroe believed he had a realistic chance to beat Lendl, but had no answer to the powerful Czech's precision from the baseline. The No. 2 seed rifled backhands past the onrushing McEnroe with regularity and his service never was threatened. McEnroe reached deuce on it only once.

Lendl also returned serve spiritedly, repeatedly hitting his shots to McEnroe's feet. McEnroe did not play badly, dropping serve only twice, but was never able to raise his game to his opponent's level.

Lendl now has a 15-14 record over McEnroe. with whom he has dueled for the past decade. He has won their last four encounters.

He is bidding for his first Grand Slam title since the 1987 U.S. Open but has lost in the semifinals in Melbourne for three straight years.