The Celtics jumped the Heat with a 29-11 first quarter and went wire to wire in a dominant display that continues to series of momentum swings.
On the flipside, the Celtics had plenty of winners, with Derrick White (13 points, eight rebounds, six assists) starring early.
Jayson Tatum led the way with 31 points including 14-of-16 free-throws, eight rebounds and five assists, while Robert Williams III returned with 12 points and nine rebounds and Al Horford was impressive with 13 boards.
Heat head coach Erik Spoelstra conceded his side simply got outplayed.
“They came out and jumped us,” he said. “More than anything our offence really hurt us at the beginning.
“They weren’t getting the purposeful execution that you need on the road. They were able to get some relief points from that and got to the free-throw line and got that lead.
“We’re not making any excuses. They outplayed us tonight. We never could get any grip on the game. Outside of these crazy runs, you’ve two really competitive teams.”
The Heat were without Tyler Herro, while Spoelstra insisted Butler’s knee issue, which saw him exit Game 3 early, was not an issue for his performance.
Celtics head coach Ime Udoka said White cramped late, while Williams was benched due to precaution on his return from injury.
On Boston’s focuses, Udoka added: “First of all taking care of the ball. That was pretty evident in the first half. We only had four turnovers, three in the first quarter.
“Making them score in the half court as opposed to getting the run-outs. Our mindset was right. We’ve got to muster that same energy when we come off a win as well as a loss.”