INGLEWOOD, Calif. (AP) _ The Los Angeles Lakers, the team of the 80s, fulfilled their coach's promise and guaranteed they would be a team for all time.

Just as Coach Pat Riley vowed a year ago, the Lakers on Tuesday night became the NBA's first repeat champions since Boston in 1968-1969. But the trip was just as difficult as it was long, with the Lakers needing three seven-game series to do it.

Los Angeles took a 15-point lead midway through the fourth quarter, then held on for a 108-105 victory over the Detroit Pistons in the final game of the championship series.

Asked if he'd guarantee a third title, Riley was about to answer when Kareem Abdul-Jabbar stuffed a towel in the coach's mouth. Finally, Riley said, ''No more guarantees.'' ''My only guarantee is that we're going to thoroughly enjoy this championship all summer. It took 115 games to get this job done. They worked for it. They won. They deserve the credit,'' he said.

The 41-year-old Abdul-Jabbar, who denied reports he would retire despite having a year left on his contract, said the Lakers' dominance is complete for this decade.

''I think we've been a great team for the last eight or nine years. From now on, people are going to have to refer to us in that light. This one sets us apart,'' said Abdul-Jabbar, who wasn't a factor in the final game with only four points and three rebounds.

Abdul-Jabbar, who scored 32 points in last year's title win, credited Riley's guarantee of a repeat title ''for not letting us get our sights down.''

James Worthy had 36 points, 16 rebounds and 10 assists in Game 7 and won playoff Most Valuable Player honors by averaging 28.5 points in Los Angeles' four victories.

''Riley created a challenge for us,'' Worthy said. ''I don't think we would have been as alert and focused this season without the guarantee. We had something to prove.''

The seventh-game victory was an unprecedented third of the playoff season for the Lakers, and their nine playoff defeats en route to the title were six more than they suffered in the postseason last year.

''I can't believe we did it,'' Magic Johnson said. ''We worked so hard against Utah, against Dallas and now against Detroit. We kept coming back, back, back. ... This was the hardest championship we've ever won.''

''I want another one,'' Johnson said.

The Lakers became the first team to win three seven-game series in one year by beating Utah and Dallas 4-3 in the Western Conference playoffs.

Pistons Coach Chuck Daly said the Lakers ''came out in the third quarter and seized the game with some ferocious defense. They scored on the break, threw a 37-point quarter at us.

''At that point, I said, 'Lights out and it could get worse.' But we went to our speed team and we got back into it.

''It was a gallant, courageous effort by our guys,'' he said.

But it wasn't enough.

''Give credit to the Lakers, they did what they said they would do, they did repeat,'' Daly said.

The Lakers, who trailed 52-47 at halftime, hit their first 10 shots of the third quarter on the way to a 15-point lead, then held off a furious rally by the Pistons in the final 12 minutes.

Led by Worthy, the victory gave the Lakers their fifth title in this decade.

Byron Scott scored 12 of his 21 points during the Lakers' 23-7 rally in the third period, which spanned the first 6:25 of the second half and gave Los Angeles a 70-59 lead. Scott capped the spurt with a 3-point goal.

''We worked so hard to get to this moment,'' he said. ''We weren't thinking about history, we were just worried about just winning this game tonight.''

The Lakers led 94-79 with 7:24 left before the Pistons rallied.

Vinnie Johnson had three baskets and John Salley five points as Detroit used a 17-4 spurt to close within 98-96 with 2:50 left.

The Pistons got within two on two other occasions before Magic Johnson hit a free throw with 1:16 to go to make it 103-100. Bill Laimbeer then missed a 3-point attempt and was unable to save the rebound. The ball went out of bounds with 1:05 to go.

After a missed shot by Los Angeles, Dennis Rodman missed a jumper with 39 seconds left.

With a sellout Forum crowd of 17,505 screaming, ''Repeat, repeat,'' during every timeout, Scott hit two free throws to make it 105-100. The Lakers missed three of their next four attempts at the line, however, and the Pistons then trailed by only 106-105 when Laimbeer hit a 3-pointer with six seconds remaining.

But A.C. Green clinched it with a layup with two seconds on the clock.

When the game ended, delirious fans swarmed over the court.

Magic Johnson added 19 points for Los Angeles. Joe Dumars had 25 points for the Pistons, Salley 17 and Adrian Dantley 16.

Isiah Thomas, despite a badly sprained ankle that had him on crutches just an hour before the game, played 19 minutes and scored 10 points in the first half, including consecutive jumpers in the final 27 seconds of the second quarter. Those shots gave Detroit the halftime lead.

But Thomas failed to score in the second half and saw only spot duty in the final minutes.

The franchise now has won 11 titles, the last six in Los Angeles and the first five in Minneapolis from 1949-54.

But it was the first time since moving to California in 1960 that the Lakers won a title with a victory in a seventh game. They lost five championship series that went the seven-game limit, four against the Celtics and once to New York.

The Pistons, making their first appearance in the championship series since moving to Detroit 31 years ago, became the first team since Seattle in 1978 to lose in the finals after taking a 3-2 lead.

The Lakers led 83-73 after three quarters and quickly extended the margin as Magic Johnson scored, then Michael Cooper - 1-for-14 from 3-point range going into the game - hit his second of the second half for an 88-73 lead with 10:49 left.

In the first six games, Worthy outscored Dantley in games won by the Lakers, with the Pistons' forward outscoring his Laker counterpart in the three Detroit victories. They began the game is if their personal duel would once again be reflected in the final score, each scoring 11 points in the first quarter. The Pistons led 23-21 at the end of the period.

Detroit scored just two points in the first 3:50, but persisted in pushing the ball inside and ran off eight consecutive points, including six by Dantley, for a 10-7 edge.

The lead changed four more times and the score was tied twice before Dumars hit a 3-pointer and Dantley converted a three-point play for a 23-19 Detroit advantage with 1:31 left in the first period.

The Pistons led 26-23 early in the second quarter before Worthy, who scored nine points in the period, started an 11-2 run with a turnaround move in the lane. His three-point play capped the spurt, giving Los Angeles a 34-28 lead.

Detroit responded with a 16-7 rally for a 44-41 edge with 2:46 left. Rodman scored six of his eight second-quarter points during the run, but he missed four of six free throws.

The Pistons won Game 1 of the championship series 105-93, handing the Lakers their first series-opening loss at home since 1981, a span of 20 playoff games. Dantley hit 14 of 16 shots from the field and scored 34 points for Detroit. The Lakers came back to win the second game 108-96 at the Forum as Worthy scored 26, then won the third game 99-86 at the Pontiac Silverdome behind Worthy's 24.

It was Dantley dominating Games 4 and 5, scoring 27 and 25 points, respectively, as Detroit won 111-86 and 104-94.

The Lakers evened the series with a 103-102 victory in Game 6, the first of the series that wasn't decided by 10 points or more. Abdul-Jabbar hit two free throws with 14 seconds left to put the Lakers ahead. Magic Johnson had 22 points and 14 of his 19 assists in the first half.

Thomas scored 43 points for the Pistons in Game 6, including a playoff- record 25 in the third quarter. Philadelphia's Joe Fulks scored 21 in a quarter during a 1947 game against Chicago.