Ray Allen resurrected the Heat with a clutch 3- pointer near the end of regulation, and Miami did just enough in overtime to force a winner-take-all Game 7 in the NBA Finals.
The instant classic at American Airlines Arena ended with Chris Bosh blocking Danny Green's 3-point attempt to seal the Heat's 103-100 victory and deny the San Antonio Spurs a fifth championship.
The Spurs wasted a 13-point second half lead and were ahead by five with 28.2 seconds left in regulation before LeBron James and Allen each connected from long range to send Game 6 to an extra session.
James scored the go-ahead bucket in OT and finished with his second triple- double of the series with 32 points, 11 assists and 10 rebounds.
"That's why you play the game until the final buzzer," James said. "It was by far the best game I've ever been a part of."
Tim Duncan had a monster 25-point first half, but managed just five after the break and went the last 21:30 without scoring as he watched a fifth ring slip through his fingers.
The Spurs have another chance Thursday but have history against them. The last five Game 7s in the Finals have been won by the hosts. The Washington Bullets were the last team to take the deciding game on the road, doing so in 1978 against the Seattle SuperSonics.
"We have to bounce back. We have to realize we have another great opportunity (Thursday)," Spurs point guard Tony Parker said. "It's going to be another great game."
The back-and-forth series saw four consecutive blowouts before Tuesday's game went down to the wire, mostly thanks to the fourth-quarter heroics from James.
With Dwyane Wade and Bosh on the bench to start the period, it was up to the league MVP and a struggling supporting cast to rally from a 75-65 deficit. Three-pointers from Mario Chalmers and Mike Miller pulled Miami within 77-73 early on, and James began attacking the rim on every possession, even after taking an elbow to the chin from Manu Ginobili.
Sans headband following the knockdown, James scored inside five times in the first 5 1/2 minutes. His block on Duncan preceded his tying layup at the other end, and on the next possession, Allen got a reverse lay-in to fall for an 84-82 lead -- Miami's first since the second quarter.
James made 1-of-2 at the foul line to complete the Heat's 8-0 run, and it was still a three-point lead for the hosts coming down the stretch.
Tony Parker answered James by hitting a stepback 3-pointer over him with 1:27 remaining, then spinning for two and a 91-89 lead inside the final minute.
Three free throws by Ginobili gave the Spurs a five-point lead before James got a second chance at a 3-pointer and connected with 20.1 seconds to go. After Kawhi Leonard split a pair at the stripe to keep it a one-possession game, 95-92, James missed from the perimeter with time winding down.
Bosh, though, secured a huge offensive rebound and kicked to Allen in the corner for a tying triple that sent the crowd into a frenzy.
"Chris made a heck of an effort to give us that second possession and found Ray, and Ray did what he's done for so many years," Heat head coach Erik Spoelstra said. "We're just looking forward to having a Game 7 in our building."
With 5.2 seconds left, Parker went coast-to-coast but was forced into a tough baseline fadeaway that fell well short as the buzzer sounded.
It was no more than a three-point game in the extra session, with consecutive buckets by Allen and James giving Miami a 101-100 lead with 1:43 on the clock. The Spurs turned it over their next two possessions, and Bosh blocked Parker's deep jumper with 31.3 seconds showing.
After Wade missed a 21-footer, Ginobili quickly drove the lane and had the ball knocked out of his hands by Allen, who was fouled with 1.9 ticks to go and sank both critical free throws.
There was contact on Ginobili's eighth turnover, and a whistle could have been blown -- at least in one player's opinion.
"We obviously believe it was a foul going down the middle. We get two free throws and we're talking about something different here," a despondent Duncan said.
Green' desperate shot from the corner was smothered by Bosh to end the thriller and keep Miami's hope at a repeat title alive.
Bosh totaled 10 points and 11 rebounds, Wade checked in with 14 points and Chalmers woke up from a three-game slumber to chip in 20 points in the win.
Leonard recorded his third double-double of the series with 22 points and 11 boards, while Parker netted 19 points on a subpar 6-of-23 shooting effort. Ginobili was limited to nine points, and Green made only one 3-pointer after hitting a Finals record 25 over the first five games.
A fast-paced start was highlighted by Leonard's dunk over Miller in transition, a throw-down that was half stiff-arm, half tomahawk slam.
There were five ties and four lead changes in the opening quarter, the last coming when Chalmers capped his 10-point frame with his second 3-pointer of the night to give the Heat a 27-24 lead in the final minute.
Chalmers, who shot 4-for-19 from the floor in the three games in San Antonio, gave the Heat their biggest lead at 40-33 with a 13-footer early in the second quarter.
That's when Duncan, who made his first eight shots, went on a personal 6-0 run to pull the Spurs within one, then rattled in a turnaround jumper in the lane to tie things at 44-44 with under two minutes left in the half.
Leonard's tip-in just before the buzzer capped a deafening 11-0 run to give San Antonio a 50-44 halftime lead.
Ginobili opened the third quarter with a 3-pointer, but the Spurs made just one field goal over the next six minutes, allowing the Heat to cut its deficit to 57-56 on Miller's take to the rim.
Parker ended Miami's 12-4 spurt with a three-point play to spark a 14-3 surge that pushed San Antonio's margin to a game-high 13 points at 71-58.
With five 3-pointers, the Spurs have made a Finals record 55 for the series, surpassing the previous mark of 52 set by the Celtics in the 2008 championship round ... The Heat have not lost consecutive games since January ... Miller stayed in Miami's starting lineup and scored eight points after going scoreless the previous two games ... The Spurs won the battle in the paint by a 60-36 margin.