BOSTON — Miami’s Big Three was as sembled for just this purpose: To dominate the bullies from Boston who knocked them from the playoffs so many times before.

LeBron James scored 35 points, Dwyane Wade had 28 and Chris Bosh had 20 last night to give the Heat a 98-90 overtime victory over the Celtics and move Miami within one game of the Eastern Conference finals. The Heat lead the best-of- seven East semifinals 3-1, with a chance to close out the series in Miami tomorrow.

“Wednesday night will be our greatest challenge that we’ve had with this group so far,” Miami coach Erik Spoelstra said. “We’ll get their best games on Wednesday. And we have to be better.”

One game after their worst performance as a threesome, James, Wade and Bosh had 83 of Miami’s 98 points and 35 of its 45 rebounds. They scored all 12 of Miami’s points in overtime; Bosh and Wade had five apiece after James’ fallaway jumper on the Heat’s first possession of the extra period game them the lead for good.

“He had some incredible ‘will’ plays there in the fourth quarter and overtime,” Spoelstra said. “We needed every bit of his talent and competitive will.”

Paul Pierce scored 27, Ray Allen had 17 and Kevin Garnett had seven points and 10 rebounds for Boston, which eliminated Miami from the playoffs last season one round after knocking James and the Cavaliers out for the second time in three years. The Celtics would need to win the next three games to have a chance to defend their Eastern Conference championship.

“These are those moments. I look forward to it,” Allen said. “Everybody on this team, we know what to do. We can’t talk about it; we just have to put our best foot forward. It’s not easy. It just makes it that much more special if we’re able to do it.”

Boston took an 84-81 lead with 2:28 left after back-to-back 3-pointers by Delonte West and Allen, but James hit a 3 to tie it and then made a left-handed lay-in with 48 seconds to play to give Miami an 86-84 lead. Pierce drove to the basket to tie it, but James lost control of the ball while he was dribbling down the clock.

Allen went for it and was bumped by James Jones, giving Boston the ball out of bounds with 19.5 seconds left and the game tied at 86. Pierce got the ball, waited out the clock and then took a high-arcing fallaway jumper in the final seconds that bounced off the rim as time expired.

The Celtics scored just four points in overtime, shooting 1 for 6 and making four of their 18 turnovers.

“We just had poor execution down the stretch,” Pierce said. “It just carried into overtime, it seemed like. We feel like tonight we beat ourselves.”