A hobbled LeBron James had 26 points, 12 assists and nine rebounds as host Miami moved within a win of the NBA championship.
James battled through a fourth-quarter leg injury to help lift the Heat to a 3-1 lead in the best-of-seven. The reigning MVP had plenty of help in this one, as Dwyane Wade added 26 points and Mario Chalmers added 25 after being nearly invisible in the first three games of the series.
Russell Westbrook exploded for a playoff career-best 43 points for the Thunder, who had several chances to pull it out but fell victim to sloppiness and inexperience down the stretch. Kevin Durant added 28 points in defeat.
Game 5 is set for Thursday night in Miami.
With the score tied 90-90 in the second half of the fourth quarter, James went down hard after attempting a cut to the basket. He got up limping and made a transition bank shot before calling to come out of the game and falling back to the court.
James was carried to the sidelines, where trainers worked on his left and right quads.
Moments after he checked back in, Durant knocked down a long pull-up jumper to put the Thunder back up by two. James responded with a line-drive 3-pointer from the top of the arc, and a Wade scoop layup put the Heat in front 99-94.
With James on the bench in obvious pain, Chalmers added a driving layup with 44.6 points remaining to restore the advantage. Westbrook answered with a difficult layup but made a critical error on the defensive end, fouling Chalmers with 13.8 seconds left on the game clock the shot clock under five.
Chalmers sank both free throws to put the game away.
Chris Bosh added 13 points and nine rebounds for Miami, which can clinch its second title with a win Thursday night.
Down three at halftime, Miami outhustled the Thunder to open the third quarter and jumped in front on a Bosh three-point play with 9:02 left. A Chalmers 3-pointer extended the lead to four, and Miami fended off repeated Thunder comeback attempts until James buried a long jumper inside a minute remaining to give the Heat a seven-point edge.
Westbrook responded with a long 3-pointer on the Thunder's last possession of the quarter, making it a 79-75 game entering the fourth.
The Thunder closed to within a point early in the final frame, but James Harden missed an easy layup at one end and the Heat converted their next two shots, including a Chalmers 3-pointer that made it a six-point game. Westbrook single-handedly kept the Thunder alive, scoring 11 straight points to close the gap to two with 6:47 left.
GAME NOTEBOOK: No team has ever rallied from a 3-1 deficit to win the NBA title. ... Wade was banged up earlier in the game, falling hard to the court after having a layup attempt blocked by the Thunder's Serge Ibaka. Play continued as Wade remained in the backcourt holding his lower back, and he spent some time on his hands and knees while being attended to during the next stoppage. ... Westbrook's 43-point performance was the highest tally in a Finals game since Wade scored 43 in the 2006 Finals against the Dallas Mavericks. ... The Heat trailed 33-19 after one, its largest first-quarter deficit of the season. ... Chalmers scored just 17 points in the first three games of the series. ... Aside from Durant and Westbrook, no other Thunder player scored more than eight points.