Celtics take a look at the film after Game 1 collapse

MIAMI — In the wake of Tuesday night’s Game 1 loss to the Miami Heat, the Celtics sounded like a football team.

Whether it was Jayson Tatum, Jaylen Brown or coach Ime Udoka, they all had to look at the “film.”

A day later, after getting together at the team hotel, the damage was fairly self-explanatory: being on the wrong end of a 39-14 third quarter, including only two field goals, five secondhalf assists after 17 in the first half and eight third-quarter turnovers, including six from Tatum.

And, above all, just about anything Jimmy Butler did to disrupt the Celtics.

“To put a guy on the line 18 times, [we’ve] just got to play smarter,” Daniel Theis said of Butler’s ability to shoot 17-for-18 from the line as a big part of his 41-point performance.

“We know he’s a big shotfake guy, so all of us just got to be smarter and put the hands back and just make him make tough shots. He had some tough shots he made, [so you] can shake his hand but can’t bail him out and put him on the freethrow line that many times because he’s a great freethrow shooter.

“That’s easy points right there; gets him a rhythm. So we got to stay away from that.”

But the Celtics feel they also have two encouraging reference points.

They responded well after losing Game 1 of the conference semifinals to Milwaukee in the Garden. And that 39-14 eyesore aside, they otherwise played well against the Heat, including as the better team in the first half.

“We have a lot of confidence in our group,” Theis said. “We won three out of four quarters [Tuesday].

“The third quarter killed us — we gave up 40 points and we had eight turnovers in the quarter. That’s more convincing for us that we can beat this team. We just have to play a full game.

“It’s kind of similar to Milwaukee in a way. They want to score off offensive rebounds and turnovers because our half-court defense is great. But like I said the third quarter killed us.”

There’s also a chance the Celtics will miss Marcus Smart (right foot sprain) and Al Horford (health protocol) for Thursday night’s Game 2 as well. The absence of both players was clearly evident in Game 1.

“Obviously we weren’t prepared for playing without Al,” said Theis. “Surprised right before the game to find out he’s not playing. It’s next man up when somebody is out, and you saw that in the first half — we played great.

“Second half, the Heat adjusted [and] packed the paint. We took a lot of contested jump shots, turned the ball over a lot, and it changed the game for them.”

Rob Williams was on the floor for much of that damage.

“It just has to be a team effort,” Theis said. “We take pride on defense, obviously, and the biggest thing with that is helping each other, realizing it’s not one guy out there to guard. There’s defensive tendency and there’s rebounding tendency, so just a team effort.”

“Obviously it’s tough losing any teammates, especially our two starters, but it’s a next-man-up mentality,” said Williams. “And it doesn’t really worry me because my guys, they know how to fight.

“And even if this starts with me or other people just stepping up and taking on that defensive presence or leading the physicality presence, whatever we got to do to step it up a notch.”