CLEVELAND – After a failed fourth quarter, the Boston Celtics didn’t seem too disappointed in their narrow loss to the Cleveland Cavaliers on Sunday night.

In the visitors’ locker room at Rocket Mortgage Fieldhouse, a few players were munching on chicken wings. A few boys exchanged jokes. After the most meaningful season of his career, Drew Peterson expressed that he believed the coaching staff was actually calling for Jrue Holiday when they told him to come into the game at the start of the second quarter.

“Every time I hear ‘Drew,’ I assume it’s Holiday,” Peterson said. “They pointed at me.”

The defending champions don’t necessarily have to react to bad results, even if they come in big games. They still realized they had missed after building a double-digit lead in the fourth quarter of their 115-111 loss to Cleveland.

“I thought they just made more plays down the stretch than we did,” coach Joe Mazzulla said. “But I think it started at the end of the third (quarter) and beginning of the fourth where we kind of had some of those empty possessions and allowed them to hang around. And when it comes to a close game, it depends on who makes more plays.”

The Celtics couldn’t stop Donovan Mitchell, who scored 20 of his 35 points in the fourth quarter. They couldn’t maintain their 14-point lead in the second half. And after falling behind by three points late in the fourth quarter, they failed to score a single potentially tying attempt over several attempts in the final seconds.

Cleveland perfectly executed its plan to repeatedly foul Boston, leaving Mazzulla’s team with no chance to tie the score down the stretch. Cleveland fouled the Celtics three times in the last 11.1 seconds before they were able to attract attention from downtown. Boston was three points behind each time because the Cavaliers continued to make their free throws on the other side.

The way Cleveland called the final foul impressed the Celtics. After taking its final timeout with 5.7 seconds left, Boston was desperate to find a three-pointer to tie the score. Mazzulla started a play in which all four Boston non-inbounders were behind the midfield line. It looked like the Celtics had played a football-style set like the Pacers used against them in the Eastern Conference finals.

Mazzulla said he wanted his players to make the defense uncertain and find a gap to make a 3-point catch attempt. In this situation, Mazzulla said other teams would typically have used a man-to-man defense.

The Cavaliers lined up in a zone.

“It was the first time a team took up some zone against them,” Mazzulla said.

The Celtics couldn’t find a chance against the Cavaliers’ zone defense. Payton Pritchard intercepted Holiday’s inbounds pass and couldn’t continue. Evan Mobley, who was in the corner, was able to foul Pritchard, preventing him from making a 3-point attempt.

“It was smart of them to go into the zone,” said Kristaps Porziņģis, who finished the game with 21 points and eight rebounds. “We obviously had some movement to get an open look, but I don’t think that was really there. Payton made a play and we got fouled, and that’s how it went. It was like adjustment against adjustment and they honestly did a good job tonight.”

Coach Kenny Atkinson suggested that the Cavaliers would normally start intentionally fouling with a three-point lead under 10 seconds. Against the Celtics, they went into strategy a little earlier.

“I think 10 seconds is kind of our thing,” Atkinson said. “But I thought, screw it, we’re going to foul. I don’t want Payton Pritchard to come down and shoot a stepback 3. You just feel it.”

Because of the many fouls, the final 34 seconds of the game lasted more than 17 minutes. The Celtics still had a chance after the last Cleveland foul. After sinking his first free throw, Pritchard intentionally missed the second perfectly near the front rim, but couldn’t execute well enough the rest of the sequence. In his rush to shoot the ball over the rim first before the Cavaliers were ready for a rebound and then grab the rebound himself, he committed a lane violation.

“Man, that happened so fast,” Jayson Tatum said. “You called it. It was just unfortunate, I think.”

Even after the Celtics blew part of a 12-point lead in the fourth quarter, they took a 97-92 lead on a fadeaway jumper by Tatum with less than four minutes left. Mitchell scored three points on each of Cleveland’s next three possessions.

“He just found different ways to create space for open looks,” Mazzulla said. “One of them was involved in a catch-and-shoot tournament. We helped on one of his drives and gave Mobley a dunk. He received two isolated specimens. So he just found ways to create space and make plays there at the end.”

The Celtics almost had one of their best wins of the entire season. With two starters missing — Jaylen Brown and Derrick White — Mazzulla had to deviate from his usual game plan. Sam Hauser started for the first time this season. Peterson, a winger on a two-way contract who had played 30 minutes in his entire career, played the entire second quarter. The Celtics usually play Al Horford and Porziņģis back-to-back, so one of them plays in the first game and the other starts in the second game. However, they sat both on Sunday, even though they had another game on Monday against the Miami Heat. Mazzulla said he wasn’t sure what that would mean for the availability of Porziņģis and Horford against the Heat.

The undermanned squad was almost enough against the talented Cavaliers, who moved to 18-3 with the win. After trailing by two points at halftime, the Celtics controlled the third quarter, trailing Tatum by 17 points. Peterson gave the Celtics 25 good minutes in by far the longest playing time of his career. Mazzulla said he wanted to reward the second-year pro after he had some “really good reps” in non-game situations recently.

“I just thought he had some really good defensive players and he defended without fouling,” Mazzulla said. “He’s physical. He’s smart. He has a knack for the ball, whether it’s rebounding offensively or moving without getting the basketball open. And I think he works really hard. So you try to find moments throughout the season where you can validate the work the guys are doing.”

Peterson said his teammates encouraged him to be aggressive with his touches.

“JT told me, ‘If you get an open shot, you better shoot it,'” Peterson said. “So I definitely learned quickly. I learned in my first games last year that it’s better not to reject open looks. So I was as aggressive as possible with the touches I got and tried to do everything I could out there.”

The Celtics didn’t do enough. Porziņģis pointed the finger at himself and said he felt “a step slow tonight” on offense and defense. He thought he needed to be in a better position and anticipate plays better, but said he felt good physically in his third game since returning from an ankle injury.

Despite some regrets, the Celtics didn’t seem to dwell on their loss. Before the season, Mazzulla said he cared more about the Celtics’ approach than their results early in the schedule. They weren’t perfect at 16-4 in their first 20 games, but Mazzulla appreciates the way his team has conducted itself.

“I think after the offseason that we had, what was really important to me was the approach to training camp, the approach to training and the approach that we take,” Mazzulla said.

“I like where we are. I think we know we’re playing good basketball, but we know we can get better. And I think that’s a healthy starting point with 60 games left. Of course we know there are things we need to work on, but we are reasonably happy with how things are going so far. So that’s important to me. We haven’t had a bad training yet. And I like the fact that we’re not reaching the peak because we have a lot of time and we need to be able to work through these things to get there. It’s like a healthy place.”

(Photo of Payton Pritchard defended by Evan Mobley: David Richard / Imagn Images)