AUBURN HILLS, Mich. — Kevin Garnett and Paul Pierce walked together, sporting black hats with green four-leaf clovers, and tried to soak up the moment when both superstars became conference champions for the first time.

"My heart is beating faster," Pierce said.

Someone asked Garnett if he needed a water.

"I'm good," Garnett said.

KG and the Big Three certainly are.

Pierce scored 27 points, Ray Allen had 17 and Garnett added 16 to lift the Boston Celtics to an 89-81 victory over the Detroit Pistons last night in Game 6 of the Eastern Conference finals.

Boston got past an old nemesis to set up a matchup with another rival.

The Celtics, 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.

"It's kind of surreal," Garnett said. "Probably hasn't even hit me yet because we haven't slept in about four days, going on five days now. Going to the Finals, I'm just hoping to get some sleep."

After playing two Game 7s, the Celtics will get a needed break before hosting Kobe Bryant and the Lakers on Thursday night.

"We're emotionally drained," Garnett said.

The Celtics are in the NBA Finals for the first time since losing to the Lakers in 1987, the third meeting in a four-year span.

The Pistons blew a 10-point lead in the fourth quarter and lost in Game 6 of the conference finals for the third straight year. They 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.

"This is really tough," said Chauncey Billups, who scored a playoff-high 29 points. "We had it, and we didn't get over the hump."

Boston entered the series without a road win in the postseason, then beat Detroit on its home court twice to win the grueling series. The NBA's top-seeded team also rallied from a fourth-quarter deficit for the first time in seven chances during the playoffs.

"It was probably the best thing because now we can say we have gone through some stuff and we're still standing," Celtics coach Doc Rivers said.

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 2 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 and turned the ball over when James Posey surprised him from behind and snatched it away.

"He looked to his left, put the ball out and I just snatched it," Posey said.

Pierce made two free throws on the possession, putting the Celtics up by six with 1 1/2 minutes to go.

Boston's Rajon Rondo scored 11 points and Kendrick Perkins added seven.