MIAMI — LeBron James could hardly stand, certainly couldn't run. Good thing all he needed to do was shoot.

Better get well fast, LeBron. You are one victory from the biggest party of your life.

A limping, grimacing James shook off left-leg cramps to make a tiebreaking three-pointer with 2:51 remaining and the Miami Heat held off the Oklahoma City Thunder for a 104-98 victory Tuesday night and a 3-1 lead in the NBA Finals that no team has ever blown.

"I was just trying to make a play," James said. "If I was out on the floor, I wanted to try to make a play with the limited mobility I had at that time, and I was happy I was able to come through."

Game 5 of the best-of-seven series is Thursday night and James will have a chance to finish a nine-year chase that started in Cleveland before he famously — or infamously — left for South Florida before last season.

"Of course it's there to think about," James said.

"I'll be ready for Game 5."

With James watching the final moments, Mario Chalmers finished off a stellar 25-point effort that matched teammate Dwyane Wade.

James had 26 points, 12 assists and nine rebounds, missing a shot at a triple-double because he was on the bench at the end after thigh cramps emerged following a fall near the Thunder basket.

The Heat needed all James could give and more to hold off Russell Westbrook. He scored 43 points for the Thunder, which wasted an early 17-point lead but was never out of the game because of its sensational point guard. Ex-Sonic Kevin Durant had 28 points but James Harden threw in another clunker, finishing with eight points on 2-of-10 shooting.

Westbrook and Durant were the only Thunder players to score in the last 16:45.

"Shots were falling," said Westbrook, who was 20 of 32. "It really doesn't mean nothing. We didn't come out with the win."

James stumbled to the court on a drive midway through the fourth quarter, staying on the offensive end of the floor as the Heat regained possession on a blocked shot, and he made a short jumper that made the score 92-90. After Westbrook missed a jumper, the Heat called timeout as James gingerly went to the court. Unable to walk off, he was carried to the sideline by teammates.

He returned to a huge roar with slightly more than four minutes left and the Heat down two, and after Chris Bosh tied the score, James slowly walked into a pull-up three-point attempt — perhaps doing so knowing he couldn't drive past anyone — and drilled the shot.

That made the score 97-94, and when Wade made a layup with 2:19 left, the Heat finally had enough room to withstand Westbrook, who kept attacking all night.

"Whatever it takes. No excuses," said Wade, who had to shake off his own aches and pains after landing hard on his back in the first half after a spectacular block by Serge Ibaka. "You don't want to leave this arena saying you missed opportunities."

Chalmers sure didn't. The player who was struggling so badly the Thunder put Durant on him in hopes of avoiding further foul trouble made 9 of 15 shots, scoring more points than he had in the previous three games.

"Mario Chalmers is a winner," Wade said. "He was due for a big game, and he came through for us."

The Heat couldn't have done it without James, who refused to let pain prevent him from taking one of the biggest steps of his career.

The Heat never got past its second Finals victory last year, with James' struggles perhaps its biggest problem as it lost the last three to Dallas. But he was at his brilliant best in this one, keeping up his scoring surge but also willingly kicking the ball out to open teammates when he was double-teamed.

He tried to play through the pain, but the Heat had to call another timeout and remove him for good shortly after his go-ahead basket.

Bosh finished with 13 points and nine rebounds for the Heat, which quickly climbed out of a 17-point hole by scoring 16 straight points, with Chalmers and backup Norris Cole helping steady the team until James and Wade got going.

James and Durant sat alone on their benches moments before the game, Durant staring quietly toward the floor and James saying something to pump himself up.

In foul trouble the last two games, Durant began the game covering Chalmers, an adjustment that freed him from the burden of defending James. It kept Durant safe from fouls — but the Thunder probably didn't count on the scoring explosion from Chalmers.

"I took that as a little sign of disrespect," Chalmers said.

Note

• Pat Riley, Heat president and former coach, was honored before the game with the Chuck Daly Lifetime Achievement Award.