MIAMI — A week ago, the Boston Celtics seemingly were too old.

Three games later, they are one victory from the NBA Finals.

And Miami — the team that was constructed with hopes of supplanting Boston as the power in the Eastern Conference — is suddenly in big trouble.

Kevin Garnett finished with 26 points and 11 rebounds, Paul Pierce scored 19 — including a huge three-pointer over LeBron James' outstretched arm with 52.9 seconds left — and the Celtics beat the Heat 94-90 Tuesday night, taking a 3-2 lead in the best-of-seven East finals.

Game 6 is Thursday in Boston.

"We've done nothing," Celtics coach Doc Rivers said. "We're playing a heck of a basketball team. So just because we're going to Boston, I told them, 'We have to play. They're not going to give it to us.' "

James had 30 points and 13 rebounds for Miami, though he went eight minutes without scoring in the final quarter. Dwyane Wade added 27 for the Heat, which got no more than nine points from anyone else.

"We wouldn't want to be in this situation, but we never get too high or too low in a series," James said. "We had an opportunity to come home and take a lead, but we didn't. So we have to go up to Boston and win a game."

Pierce's three over James put Boston ahead 90-86.

The Celtics, listed as eight-point underdogs, were behind by 13 in the second quarter and down nine in the third. They answered both times — prevailing on a night where they shot a mere 41 percent, and got outrebounded 49-39.

"We stayed with it," Garnett said. "We had a rough first quarter, first half. We got our stops and made our run ourselves. And when we had to, we had stops."

Boston scored 22 of the game's last 34 points.

"Every time we got them down, they made runs," James said. "They made us stagnant offensively, got stops and got back in the game."

Heat forward Chris Bosh played for the first time since straining a lower-abdominal muscle in Game 1 of Miami's second-round series against Indiana. He got a big ovation and had nine points on 3-for-8 shooting.

Miami Beach police said a masseuse collapsed at Bosh's home and was pronounced dead at a nearby hospital Monday night. Police said they did not find signs of foul play. Bosh and his wife, Adrienne, released a statement through the team expressing sadness for the masseuse's family.

"Shortly after she arrived, she fainted and lost consciousness," read part of the statement. "We called 911 and emergency personnel arrived at our home shortly thereafter."

Note

• Oklahoma City, which has won three in a row, has a chance to eliminate the visiting San Antonio Spurs on Wednesday in Game 6 of the West finals. The Thunder hasn't lost at home in this year's playoffs.

"We have a great opportunity, we're on our home floor but that doesn't guarantee automatic victory," Oklahoma City coach Scott Brooks said. "They're not going to give us the game. They're not just going to say, 'We've lost three in a row, we're going to give in.' We know we have a tough challenge ahead."