Jayson Tatum has been criticized for his performance against the Warriors. On Thursday, he finally had a chance to respond.

Jayson Tatum's 3-pointer in overtime gave the Celtics a 118-111 lead.John Tlumacki/Globe Staff

The Warriors are too talented, too experienced, and too precise to allow Jayson Tatum one of his customary stellar games. They were going to provide resistance, throw multiple defenders, multiple looks, and Tatum-stopper Andrew Wiggins at him for all of his 48 minutes.

Tatum has been heavily criticized for his NBA Finals performance for the past seven months, and he’s responded with an MVP-type season. But it would mean little in the social media world if he floundered against his biggest challenger.

Thursday night was a struggle for Tatum. He missed 18 shots. He committed seven turnovers. The Warriors capitalized on his mental lapses, forcing him to take nothing for granted, not even simply dribbling the ball up the floor.

He was challenged, and instead of relenting he prevailed with one of the more meaningful games of his career. The Celtics rallied in the fourth quarter, and then held on in overtime for a 121-118 win at TD Garden.

The Warriors remain the defending champions. The Celtics remain the primary contenders to succeed them, but psychologically it was significant for Tatum, even if he described it as another regular-season game.

He played a career-high 48 minutes 7 seconds, including the final 41 minutes of the game. He willed his way to a productive game, scoring 34 points with a career-best 19 rebounds, plus 6 assists and 3 steals to offset those seven turnovers.

It wasn’t a classic performance. It wasn’t Tatum at his best, but it was Tatum as his good enough. The difference between Thursday and the Celtics’ Dec. 10 shellacking at Golden State was poise.

“I think the first time we played them in San Francisco, I felt like we bought into that hype, the rematch of the Finals, ABC game, first time back since we lost, everybody wanted to win so bad,” Tatum said. “I think that was the first time all season we played out of character. We played tense. And we had a talk about it [Thursday]. We lost. We lost the championship, no one win can bring that back.”

But the Celtics had to prove to themselves they could beat the Warriors, despite Golden State’s current precarious state as a below-.500 team with 18 road losses.

It wasn't easy for Jayson Tatum and the Celtics Thursday night, but they still managed to come away with the win.John Tlumacki/Globe Staff

Of course, the Warriors were going to play like champions Thursday. The regular season has seemed like one big distraction for a team with a championship pedigree. They have elite talent. They can shoot with any team in the NBA, and defend brilliantly when they desire. But the desire and fortitude have been fleeting this season.

It wasn’t on Thursday night. If the Celtics were going to beat the Warriors, they were going to beat engaged Warriors. It was the response of champions.

“Obviously, they’re one of the better teams in history,” said Jaylen Brown. “When they come ready to play, they’re tough to beat. For us to be able to battle back and stay together even in moments when we were down in the fourth quarter, that was the biggest part of the win, just being able to stay consistent.”

Brown also struggled. But he drained the tying 3-pointer with 18.6 seconds left that sent the game to overtime. After missing the last three games with right adductor tightness, Brown looked a step slow until the fourth quarter, but he began hurting the Golden State defense with post drives.

Tatum still looked meek at times against Wiggins, who did not play in the December meeting. But he began devising ways to make plays without having to force shots. During the Finals, Tatum took on multiple defenders with low-percentage layups. On Thursday, he was able to get to the rim, although he did not finish as often as usual.

“I’m glad we won; it wasn’t pretty,” Tatum said. “But this was a great win for figuring it out. Nobody besides Al [Horford] shot great. It was just toughness plays, moving on to the next, doing whatever it takes to win, and those are the most rewarding wins.”

It’s not that the Celtics would have been considered fraudulent if they had lost this game, but they would have been considered beatable. Two losses to the Warriors, a team that has recently dropped games to the Pistons and Magic, a team that hasn’t won consecutive road games all season, would have been a major blemish on their resume.

So, the victory was critical, for now. They are going to be plenty of other contenders coming out the West, but the Celtics have beaten them all this season. The Warriors had the recipe to defend Tatum: Pack defenders in the paint and force him to drive left, where he isn’t has decisive and is capable of mistakes on passes.

The Celtics countered with winning plays: offensive rebounds, defensive gems at the rim, holding the Warriors to one shot. They won an ugly game but it was a pretty win, especially for Tatum, who listened to his critics for the past seven months about how Wiggins’s defense frazzled him into mistakes.

He still made a handful of mistakes Thursday, but he didn’t allow his miscues to affect his approach. The Finals made him mentally stronger.

“Just trying to put the past behind us,” Tatum said. “Tip our hat off to the Warriors. They won the championship. They beat us. There’s nothing we can do about that. This win doesn’t avenge the last playoffs. It’s a good team win and move on to the next one.”