A remarkable triple-double from Jimmy Butler has lifted the short-handed Miami Heat to a shock 115-104 win over the Los Angeles Lakers, breathing new life into the NBA Finals.

Butler finished with 40 points, 11 rebounds and 13 assists as the Heat cut the Lakers' series lead to 2-1 - doing so with starters Bam Adebayo and Goran Dragic unable to play because of injury.

"I tell Coach all the time, 'I'm ready for this,'" Butler said. "The biggest stage, whatever you ask me to do, I can do."

His coach, Erik Spoelstra, has clearly listened.

"This is what he wanted, this is what we wanted," Spoelstra said.

"It's really hard to analyse or describe Jimmy until you actually feel him between the four lines.

"He's a supreme, elite competitor and we needed it."

It was the third 40-point triple-double in finals history, Butler coming up with the game of his life when the Heat needed it most.

He was 14 for 20 from the field, and after the Heat surrendered a double-digit lead early in the fourth he made sure this one wouldn't get away.

"He's one of the best competitors we have in our game," the Lakers' LeBron James said.

"Love that opportunity. For me, personally, I don't know how many more opportunities I'm going to have so to be able to go against a fierce competitor like that is something I'll look back on when I'm done playing. I'll miss those moments."

Game four is on Tuesday night (Wednesday morning AEDT).

Tyler Herro and Kelly Olynyk each had 17 points for Miami, who also got 13 from Duncan Robinson and 12 from Jae Crowder.

James had 25 points, 10 rebounds and eight assists for the Lakers, while Kyle Kuzma and Markieff Morris each had 19 points off the bench. Anthony Davis managed 15 for the Lakers.

Whenever the Heat looked ready to pull away and grab control of the clash, the Lakers always found a way to find their best gear.

A 13-point Heat lead in the early going? The Lakers had the lead back in less than five minutes.

A 14-point Heat lead after a 10-0 run to start the second half? The Lakers scored the next eight.

A 12-point Heat lead late in the third? It took the Lakers less than five minutes to put together a 20-6 run, taking the lead back at 91-89 with 8:55 left on a layup by Rajon Rondo.

But the rest of the way was all Miami, Butler simply unwilling to let his team go down 3-0. The only other time Miami was down 2-0 in a finals was 2006, when Dwyane Wade took over and led the Heat all the way back.

This time, it was Butler in that role.