Kiki Vandeweghe and Mychal Thompson each scored 17 points today, allowing the Portland Trail Blazers to beat Los Angeles, 115-107, to remain alive in their Western Conference semifinal playoff series.

The Trail Blazers, maintaining their record of never being swept in a playoff series, trail the best-of-seven series, 3-1. Game 5 is Tuesday night at Inglewood, Calif. Los Angeles has won 21 straight home games.

"If the guys wanted to go home, this was the perfect opportunity," Portland's Clyde Drexler said. "But this team has a lot of character. I just hope we can carry it over down there."

Los Angeles suffered its first playoff loss this season in seven games. It was also the Lakers' first defeat since a 122-108 loss to San Antonio with six games left in the regular season.

Magic Johnson led the Lakers with 31 points and 13 assists. Kareem Abdul-Jabbar had 21 points and 17 rebounds.

Drexler and Kenny Carr each had 15 points for Portland. Drexler also had 10 assists, seven rebounds and six steals. He keyed a trapping defense that forced 28 Los Angeles turnovers.

"We had 17 turnovers in the first half because we were not ready for their second unit and the trap," said Lakers Coach Pat Riley. "I don't mind turnovers so much but when they outscored us by 19 points in the quarter, it disturbed me."

"We were confident," said the Lakers' James Worthy, "but we didn't think they would lay down for us. We expected them to play physical."

Trailing by 40-39 in the second quarter, Portland went on an 11-1 run to take a 50-41 lead with four minutes left in the half.

Portland's lead grew to 16 points early in the second half. After three periods, Portland led, 86-74. Los Angeles closed to 108-105 on Johnson's two free throws with 1:13 to play.

After Drexler made a steal, Thompson's dunk with 30 seconds left gave Portland a 110-105 lead. Thompson then made four free throws in the final seconds.

Thompson was fouled by Los Angeles because of his reputation as an erratic free throw shooter. "It's a big mistake on their part," he said. "I said to myself, 'Just relax and think about lying in the sunshine with a Mai Tai in one hand and my girlfriend Tina in the other.' "

For the first time in the series, Portland was not beaten badly on the offensive boards. The Trail Blazers outscored Los Angeles, 20-15, on second-chance points.