NBA: Playoffs-Miami Heat at Boston Celtics

Celtics guard Jaylen Brown, center, drives to the basket against Miami’s Max Strus, right, and Victor Oladipo Saturday night.

The Boston Celtics’ veterans all said the right things in anticipation of a crucial Game 3 against the Miami Heat, according to C’s coach Ime Udoka. Guys with the playoff chops to talk with authority warned the rest of the team: Be careful; be wary.

The Celtics had just smacked the Heat in Miami in Game 2, stealing home-court advantage to tie up the Eastern Conference Finals at a game apiece. As the series shifted to Boston’s TD Garden, the vets cautioned their team to “be prepared, knowing they’re going to come out with their best hit,” Udoka said.

Those words came from the likes of Marcus Smart, Al Horford, Jaylen Brown and Jayson Tatum — the undisputed leaders of the team. They spoke up during shootarounds and team meetings as they wanted to ensure the team was in the right mental space.

The right words were said … then the actual game tipped off. The Celtics failed to match the Heat’s physicality and never led in a 109-103 Game 3 loss Saturday. By the end of an embarrassing first quarter where they were outscored 39-18, the Celtics heard boos from a Garden crowd that was as juiced as possible before the game.

“We didn’t think that it was all of a sudden going to be an easy series and they were going to roll over,” Udoka said. “We bounced back from Game 1 to Game 2, and they were going to do the same. We had to match that and came out flat for whatever reason.”

The Heat didn’t just throw the first punch Saturday; they kept attacking the Celtics until there was no doubt about their intentions. They were up by double digits just mere minutes into the game as the Celtics had no answers in another embarrassing quarter. Boston missed easy layups and at the same time allowed Miami to get into a flow on offense.

Bam Adebayo, who put up a double-double with 31 points and 10 rebounds, said the Celtics in Game 2 “beat us like they stole something.” Naturally, that was going to wake up the Heat, he said, and they clearly wanted to send a message. Just like the C’s predicted they would — it’s just that Boston still didn’t have a response.

“You’ve just got to give them credit,” Horford said. “They were just like a wounded animal. They came out fighting. For whatever reason, we just didn’t have that same sense of urgency.”

The Celtics still have a chance to bounce back and win Game 4 to tie up the series 2-2. It’s not the first time they’ve dealt with similar adversity; look no further than their comeback series win against the Bucks just a week ago.

Boston also boasts a track record where it can clearly learn from a loss and show some resiliency. The C’s haven’t dropped back-to-back games since March 30, and there’s a reason for that as they have shown a killer instinct coming off losses.

But the Celtics have been mistake-prone — especially in games that aren’t necessarily a must-win. They posted 24 turnovers in Game 3, and the only reason the Celtics were somewhat in the game was because of a large free throw disparity against the Heat.

“It looked like we were kind of wilting to their pressure and started complaining to the refs and took us out of the game from the start,” Udoka said. “But disappointing to come out that flat in a conference final game.”

Even when the C’s were close to a comeback in the fourth quarter, they let the game slip away because of their turnovers. It didn’t help that Tatum had one of his worst games of the postseason while the starting lineup combined for a startling 22 giveaways.

The Celtics will likely come out in Game 4 Monday night playing the hunted role — similar to the Heat in Game 3. The C’s showcased their mental edge when they blew out the Heat in Game 2; that’s what they’ve done this entire season.

But the Celtics have fans dreaming of an NBA Finals run and perhaps a championship. Neither of those things are off the table at this point, even if the C’s are down 2-1 to the No. 1-seeded Heat and coughed up home-court advantage.

If the Celtics do want to see those championship aspirations come to fruition, though, they’ll need to cut down on their mistakes they’ve showcased in these playoffs. It wasn’t just a one-game sample size Saturday. Instead it’s arguably slowly becoming a trend where the Celtics play well for large portions of the game, but let the game slip away in one disastrous stretch.

“We started out flat,” Brown said. “Seemed like we was looking around too much instead of playing the game. They got it going and they got stops and made shots, and we didn’t in the first half. But we didn’t match their intensity out of the gate.”