“It was a great energy game,” Celtics forward Jaylen Brown said. “Today was not one of those regular-season normal games where it’s whatever. Tonight was a good day for basketball.”

The jolt provided by the lively atmosphere was particularly important for the Celtics, whose workloads increased substantially.

In a rare admission, coach Joe Mazzulla said the rivalry and the setting played into his decision to lean so heavily on his stars.

“I feel like there’s moments that you give those guys chances to be able to be a part of that,” he said. “Everybody on this roster is playing for a legacy, and you do it together, and I felt like that was a great moment for them to be able to compete at a high level for as long as they wanted to.”

Jayson Tatum did not sit in the second half and played 45 minutes, 26 seconds, a career high for a regular-season game that did not go to overtime. He finished with 40 points, 12 rebounds, and 8 assists.

Brown played 41:37, spending much of the night mimicking last season’s Finals script by hounding Doncic at one end of the floor and attacking him for baskets at the other. Brown scored 31 points.

And 38-year-old big man Al Horford logged 37:20 and more than held his own during long stretches as the Lakers’ primary target in isolation. He rumbled down the court for one fast-break dunk and finished with 14 points, 9 rebounds, 4 assists, and 3 steals.

“I got to watch five possessions of him defending at a high level,” Mazzulla said, “and at one point, I wasn’t coaching. I was just watching him, and I was like, ‘Man, this guy’s a future Hall of Famer. I get to watch this for free.’ ”

Doncic had 34 points to lead the Lakers, but he was stripped three times in the opening quarter and appeared to be laboring through stretches of the game. LeBron James had 22 points, 14 rebounds, and 9 assists, but he strained his groin during the Lakers’ fourth-quarter comeback and missed the game’s final seven minutes.

It’s unclear how long James will be sidelined, but it is quite likely that the Lakers’ surge will stall as long as he is out.

Coach JJ Redick, whose team played an overtime game in Los Angeles on Thursday night before taking a cross-country flight to Boston, chalked up Saturday’s loss to some uncharacteristic “brain fog execution” following the long trip.

Tatum brushed off the possibility of Saturday’s game being the Finals preview that everyone in the NBA’s league office is surely hoping for, and James made it clear that his team still has plenty to prove before even thinking in those terms.

“We’re not where they are, the defending champion,” he said. “And they’ve been playing basketball together for a long time. And they’ve got a great chemistry and know what they want to do. We [acquired Doncic] late in the season, and we’re still trying to build.”

The Celtics have won 14 of 17 games and continue to distance themselves from the mild angst that was created by an uneven January.

“I don’t know if I learned anything [from this stretch],” Horford said. “I would just say I know what we have. I know that when it’s time to go, we’ll be ready to go.”

Celtics center Kristaps Porzingis missed his fifth consecutive game to an illness. The Lakers were without forward Rui Hachimura (knee) and center Jaxson Hayes (knee).

The Celtics appeared to be in control after holding the Lakers to a 13-point third quarter in which Los Angeles committed six turnovers. Boston held a seemingly comfortable 90-69 lead in the opening minute of the fourth, but the win would not come easily.

The Lakers unspooled a quick 16-2 run that was capped by a James layup with 7:05 left that made it 92-85, but the Lakers superstar was injured on that play. He limped off the court soon after and watched the remainder of the game on a television in the locker room.

The comeback attempt would be left in the hands of Doncic, and for a moment it appeared that he might be up to the task. He hit a jumper and a pair of free throws before banking in a 3-pointer with 4:36 left that made it 99-95 and sparked some anxious groans inside TD Garden.

But Brown let the shot clock wind down before calmly drilling a 3-pointer over Doncic from the top of the key, Tatum added another 3-pointer with 2:30 left that made it 105-95, and the lead was never in danger again. The Celtics could soon take a moment to savor this regular-season win that did seem to mean more than most others.

“It’s special to be a part of this rivalry with the guys that we have on both sides,” Tatum said. ”You want to be a part of moments like this.“

Adam Himmelsbach can be reached at [email protected]. Follow him @adamhimmelsbach.