BOSTON -- The day before his short-handed Heat sought to even the score with the heavily favored Celtics, Miami coach Erik Spoelstra made an intriguing comment about his team's identity.

After being deluged by Boston's 3-point shooting in Game 1 of the Eastern Conference first-round series, Spoelstra said his team needed to do a better job of letting it fly to keep pace.

"I understand the math of it," Spoelstra said, before adding, "We're not going to shoot 50 of them. That's not realistic."

Maybe 50 3-point shots wasn't quite realistic, but the upset-minded Heat did just fine with 43 attempts Wednesday night. And by finishing with a playoff franchise-record 23 treys, the Heat beat the Celtics 111-101 on the road in Game 2 to even the series at 1-1.

The series moves to Miami for Game 3 on Saturday.

The sheer nature of Wednesday's upset is one of the reasons Game 2's outcome was remarkable. Miami trailed by as much as 34 in Game 1, prompting many to believe that, without star wing Jimmy Butler or starter Terry Rozier, this would be a four-game sweep.

Instead, the Heat became the first playoff team in the past 30 years to win by double digits despite being an underdog of 14 points or more.

"We've been doubted a lot through our playoff runs, people saying we couldn't do a lot of stuff that we did," said Miami big man Bam Adebayo, who had 21 points on 9-of-13 shooting and 10 rebounds. "So for me and my team, why lose belief now? Our backs are against the wall. Everybody's against us. So just use that as fuel.

"Our guys believe we can win. So let's make it mano a mano -- a cage fight. Let's hoop."

Miami's ability to shape-shift into a 3-point gunning team one game after being lit up from beyond the arc by a five-out, floor-spacing Celtics team was highly impressive. An NBA playoff-record 62.2% of the Heat's points came from their 3-point shooting in Game 2. It was the complete opposite in Game 1, during which just 38.3% of the club's points came from behind the 3 line.

Miami had connected on more 3s by halftime of Game 2 (13) than it had in all of Game 1 (12).

Following Spoelstra's edict, Miami wing Caleb Martin said he and his teammates came out looking to shoot whenever they were open.

"I think it was realizing that being passive [as shooters] hurts us. We'd just be playing into their game plan," said Martin, who got booed relentlessly whenever he touched the ball after his late-game midair collision with Celtics star Jayson Tatum in the series opener. "We're too good of a shooting team to hesitate from 3."

Tyler Herro's Game 2 turnaround was the biggest. After scoring 11 points on 13 shots in the opener, he had 24 points on 13 shots, including six 3-pointers, and added 14 assists (the second most in a game in Heat playoff history).

"Based on how we look right now [in terms of injuries], he's going to be involved one way or another, and sometimes that's going to mean making the right play over and over and over again," Spoelstra said of Herro. "And he made the right read repeatedly tonight."

Down three at halftime, the Heat took the lead and got some separation in the third period. Aside from catching fire -- Miami was 6-for-9 from deep in the quarter -- the club also limited Celtics center Kristaps Porzingis whenever he got the ball in the post. Porzingis finished 1-for-9 from the field and was a minus-32 on the night.

It clearly disrupted the flow of Boston's usually steady offense and forced Tatum (28 points) and Jaylen Brown (33 points) to do a bit too much off the dribble.

"They're obviously undersized and very athletic," Celtics guard Jrue Holiday said. "They've always swarmed and not let KP go one-on-one."

Miami's victory moved Spoelstra to 10-3 in his career in Game 2s after dropping the first game of a playoff series. Of those who have coached 10 such games, only Frank Vogel, who is 8-2 after a Game 1 loss, has a better winning percentage in NBA history.

With the Heat being a considerable underdog, it might be tempting to write off their hot shooting night as an anomaly. But doing so might be selling their recent history with the Celtics short, including their conference finals victory over Boston as an underdog last season. Wednesday's outing marked the fourth time in the past two postseasons that Miami has shot 50% or better from beyond the arc against Boston. No other team has hit that figure more than once against a playoff opponent in that span.

Celtics coach Joe Mazzulla said the natural adjustment after Miami's historic shooting performance would be to press up on the Heat's shooters more. But he cautioned against the notion of overcorrecting.

"We're going to have to find a balance, because a lot of those shooters are also good drivers and are good at getting downhill," Mazzulla said. "We have to find that balance of making sure we can close out appropriately so we don't open up the other side of that."