Boston Celtics forward Paul Pierce (left) hugs coach Doc Rivers after the Celtics defeated the Detroit Pistons 89-81 to win the NBA Eastern Conference finals on Friday night. - AP

AUBURN HILLS, Michigan (AP):

THE BOSTON Celtics booked a place in the NBA finals for the first time in 21 years by beating the Detroit Pistons 89-81 on Friday night, winning the series 4-2.

Boston, who locked up with Detroit many times in the 1980s, will now rekindle another classic series in the NBA finals against the Los Angeles Lakers.

When the Celtics last made the finals in 1987 they lost to the Lakers in what was their third meeting in four years - a clash of dynastic teams and iconic players such as Boston's Larry Bird and Los Angeles' Magic Johnson.

Pistons eliminated

The Pistons were eliminated on their home court for the first time during a six-year run that included a trip to the conference finals each year and the 2004 title. Boston entered the series without a road win in the postseason, then beat Detroit on their homecourt twice to win the gruelling series.

After being forced to Game Seven twice in the play-offs, the Celtics will get a welcome break before hosting Kobe Bryant and the Lakers on Thursday.

emotionally drained

"We're emotionally drained," Kevin Garnett said.

Detroit's Chauncey Billups scored a playoff-high 29 points, but much of the rest of the team had lacklustre efforts - especially Rasheed Wallace. At one point Billups had 21 points, matching the total for the rest of the team.

Wallace scored just four points on 2-of-12 shooting and had three turnovers in what might have been his last game as a Piston and could have been Flip Saunders' last as Detroit's coach. President of basketball operations Joe Dumars will likely make some sort of changes on the bench, the court or both.

"I'm sure that's something Joe and I will sit down and evaluate," Saunders said.

After it was 58-all, Detroit closed the third quarter with a 10-2 run and took their first lead since midway through the opening quarter.

Just when it seemed the Pistons might be in control with a 70-60 lead early in the fourth, the Celtics scored nine points in less than two minutes and went on a 19-4 run that put them ahead 79-74.

Billups' three-point play pulled Detroit to 83-79 with 2:24 left, then the Pistons wasted a chance to get closer. Tayshaun Prince grabbed a loose ball after a Boston miss when James Posey surprised him from behind and snatched it away.

Pierce made two free throws on the possession, putting the Celtics up by six with 90 seconds to go.

"It was the best fourth quarter we played all play-off long," Paul Pierce said.

The Pistons failed on their three-pointers down the stretch and couldn't take advantage of Garnett missing two free throws with 36 seconds left.

running out of chances

Detroit lost Game Six of the conference finals for the third straight year and with only one title and two NBA finals appearances during their impressive six-year run, the franchise may be running out of chances to capitalise on this playing group.

The Celtics, meanwhile, validated their bold and expensive move of adding Garnett, Ray Allen and Pierce this season. They played key roles in the decisive fourth quarter, helping Boston outscore Detroit 29-13.