Dwyane Wade had 25 points, seven rebounds and seven assists for the Heat, who were in this same position through three games last year, then didn't win against the Dallas Mavericks.

James's 3-pointer sent the Heat to the fourth quarter with the lead, and he scored five straight Miami points when the Heat were building just enough cushion to hold off another late flurry by the Thunder.

Kevin Durant had 25 points for the Thunder, but picked up his fourth foul in the third quarter and had to go to the bench when they had seemed to have control of the game. Russell Westbrook finished with 19 points.

The Heat survived their own fourth-quarter sloppiness by getting enough big plays from their Big Three.

James scored 30 and 32 points in the first two games, his two best finals performances. He fell just shy of another 30-point effort but reached his 20 points for the 20th time this postseason, two shy of Wade's franchise record set in 2006.

"It's all about chemistry," James said. "We understand where we like to get the ball, what we like to do in close situations, and it's good to see us execute down the stretch. But more importantly it was great to see we were able to get stops. That's where the game is won and we did that."

Chris Bosh had 10 points and 11 rebounds for the Heat, who can win a second title by winning the next two games at home.

They seemed out of it when Oklahoma City opened a 10-point lead midway through the third. But Durant went out, Thunder coach Scott Brooks decided to sit Westbrook with him, and the Heat charged into the lead by the end of the period.

The Thunder had grabbed their last lead at 77-76 on James Harden's basket with 7:32 left. James answered with two free throws about 20 seconds later, and the teams would trade turnovers and stops over the next couple of tense minutes.

Wade then converted a three-point play, and another minute went by before James powered to the basket, Durant trying to get in position to draw a charge but watching helplessly as he picked up his fifth foul. James made the free throw for an 84-77 advantage with 3:47 to play.

After another basket by James, the Thunder had one last burst, ripping off six straight points to get within one before Bosh made a pair of free throws with 1:19 to play. Durant missed badly on a wild shot attempt, and the Thunder missed another chance when Westbrook was off from behind the arc.

James hit a free throw for a four-point lead with 16 seconds to go and Wade added two to close it out.

"It's very hard," James said. "Both teams are very active defensively and both teams make it hard on one another in the half court so when you get stops you try to get early offense, it always helps and we were able to do that a little bit."