The Heat had led by seven points with 6:31 left, but Dallas’ Dirk Nowitzki led a comeback with 12 straight Mavericks points to level the score going into the dying stages. But he couldn’t finish the comeback, missing a tough jump shot as time expired.

Miami got into this tight situation in the series by blowing a 15-point lead in the last quarter of Game 2. The Heat, which had wasted a 14-point earlier in the game, had an 81-75 cushion with more than six minutes remaining. They knew Nowitzki would drive Dallas’ rally, and he did six free throws, a layup, a dunk and a tough jumper.

But after Bosh’s clutch shot, Nowitzki’s streak ran out.

He tried passing out of a double team and threw the ball away, then hit the back iron on a jumper at the buzzer.

“This is a total win,” said Dwyane Wade, who led Miami with 29 points and 11 rebounds. “You want to win the game on the defensive end of the floor and we got a stop.” The Heat go into Game 4 on Tuesday night needing only two more wins to clinch the championship.

Bosh, a Dallas native who’d been 0-8 in his hometown, scored 18 points, including seven in the fourth quarter.

LeBron James added 17 points and nine assists. But he also had four turnovers, including a pair during the fourth quarter that helped bring Dallas back. Mario Chalmers added 12.

Udonis Haslem had only six points, but his tough defense on the final two possessions saved the Heat. When Nowitzki’s final shot from the top of the key missed, Haslem swung his arms and screamed in delight.

Nowitzki finished with 34 points, but didn’t get much help. Jason Terry scored 15 and Shawn Marion had 10, but both were shut out in the fourth quarter.

Wade was at his dynamic best from the start, looking like the guy who soared and scored the Heat past Dallas and to the title in ‘06.

Most of his baskets came in the paint — where the Heat outscored the Mavs, 40-22 — and many of them were spectacular. But he also stemmed Dallas’ rally by hitting a go-ahead jumper over Jason Kidd for Miami’s second-to-last basket.

James went more than 6 minutes before taking his first shot, but certainly made it worth the wait — a drive through the teeth of the defense for a powerful dunk. He also had a two-handed jam in the second half that put Miami up by 13.

The Heat just couldn’t put the Mavs away. Dallas would surge close or ahead, then Miami would turn it up again.

The final 18 minutes played out with both teams realizing any possession could change the game and the series.

Heat coach Erik Spoelstra talked about wanting his players to get back to their identity of being “an aggressive, attacking team that tries to get into the paint, to the rim, to the free throw line.” They followed that script to a 14-point lead late in the second quarter, then fell into the same bad habits they showed at the end of Game 2, letting Dallas get within 47-42 at the break.

Maybe Miami players just got bored because things were coming so easily.

James and Wade seemed to get whatever shot they wanted, whenever they wanted. But they kept trying to get others involved. They especially force-fed Bosh, even though his left eye was swollen from an early, accidental poke by Jason Kidd; he missed 7 of 9 in the first half.

The Heat also made things tough on Nowitzki by keeping him from even getting the ball at stages. He took only two shots in the first quarter. He didn’t start getting free until Miami’s lead grew and guys were less intense on defense.