updated 1:25 a.m. ET June 9, 2008

BOSTON - The Boston Celtics left the comforts of home exalted and exhausted, halfway to hoisting a 17th NBA championship banner.

They’re up 2-0 in the NBA finals.

But they needed some of their leprechaun’s luck to get there.

Paul Pierce, darting around the parquet floor with ease, scored 28 points, unknown Leon Powe added 21 and the Celtics held off a remarkable rally by Kobe Bryant and the Los Angeles Lakers for a 108-102 win Sunday night in Game 2 of these trip-down-memory-lane finals.

The Celtics had to work every second to get the win.

Up by 24 points in the fourth quarter, they nearly blew it.

“We’re happy because we won, but we definitely learned a lesson,” Pierce said.

The Lakers trailed 95-71 with less than 8 minutes to go, but used a 31-9 run to pull to 104-102 on two free throws by Bryant with 38.4 seconds left. Pierce, though, made two free throws, then blocked a 3-pointer by Sasha Vujacic, and James Posey made two free throws with 12.6 seconds left to ice it for Boston.

“We’ve got to play through the game for 48 minutes, and I didn’t think we did that,” Celtics coach Doc Rivers said. “I thought we got cute when we got the lead.”

The Lakers, who dropped 41 points on the league’s defensive team in the final 12 minutes, simply ran out of time.

“It’s something that we can take from,” Bryant said of the furious but failed comeback. “We played with a sense of desperation and aggression. I think that’s something to take home and learn from.”

Boston enjoyed a huge free-throw advantage, going 27-for-38 from the foul line, while the Lakers were just 10-for-10.

The whistles were one-sided.

“I didn’t notice,” Bryant said, cracking a smile.

Pierce wasn’t slowed by a sprained right knee suffered in the series opener, when he was carried from the court and plopped into a wheelchair. The Boston captain paced the Celtics, who are back in the finals for the first since 1987, when Larry Bird was the main man and gasoline cost 91 cents per gallon.

As usual, Boston’s Big Three — Pierce, Ray Allen (17 points) and Kevin Garnett (17) — were the ringleaders but Powe, a second-year reserve had the game of his career, adding his 21 points in 15 minutes that may make him a Celtics fan-favorite for life.

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Powe, who played a total of 68 seconds during one stretch of 13 games during the season, scored six points to close a 15-2 run ending the third quarter that gave the Celtics a 22-point lead. The quick burst had the Lakers California dreaming. At one point in the fourth quarter, Boston fans discarded the familiar chants of “Beat L.A.” for cries of “Le-on Powe!”

“He was terrific,” Rivers said.

Rajon Rondo had a career-high 16 assists and Garnett added 14 rebounds for the Celtics, back in the finals for the first time since 1987.

Game 3 is Tuesday night at the Staples Center in Los Angeles, where the Lakers are 8-0 in the postseason and have won 14 in a row at home since March 28. Bryant had better hope the rims there are a little kinder than the ones in TD Banknorth Garden.

Bryant, who pledged to bounce back from a sub-par Game 1, scored 30 points — 13 in the fourth — on 11-of-23 shooting. In four losses to Boston this season, Bryant is just 35-of-93 from the field and can’t seem to get the same easy looks he enjoys against every other team.

Pau Gasol had 17 points and 10 rebounds for the Lakers, who were so far down in the fourth that many of their purple-and-gold clad fans who came to cheer them on, headed toward the exits and maybe to Logan Airport for the trip out West.

But Bryant brought them back — almost all the way.

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