Jayson Tatum wasn’t about to let the Celtics stumble again, so he took matters into his own hands

Jayson Tatum (right) ran into Alex Len of the Wizards on his way to the basket in the first quarter.Jim Davis/Globe Staff

Celtics forward Jaylen Brown sat in a blue chair in the second row of Boston’s bench on Tuesday night wearing a black hat and white T-shirt, his surgically repaired left wrist in a cast. His absence during this postseason turned possibility into a long shot for the Celtics, and it left many wondering whether they even had enough to win Tuesday’s play-in game against the Wizards.

While losing an All-Star forward is a substantial blow, the Celtics are a rare team that has two of them. Jayson Tatum has sparkled during this otherwise humbling season. And in this game, he made it clear he would not let his team stumble. Not here.

Tatum erupted for 50 points and led Boston to an emphatic 118-100 win over the Wizards at TD Garden. The All-Star forward made 14 of 32 shots and 17 of 17 free throws.

Wizards coach Scott Brooks said after the game that Tatum will be an MVP soon. Celtics point guard Kemba Walker smiled when that statement was relayed to him.

“He’s right about that,” Walker said.

After the game, as Tatum completed a postgame television interview while standing near one of the baskets, a few hundred fans from the lively crowd of 4,789 gathered in the lower bowl near him, snapping pictures, holding up signs, and shaking their heads in amazement.

When Tatum removed his headset and walked toward the locker room, they roared, and Tatum touched his heart and pointed to them. Everyone was happy.

“I just wanted to be aggressive tonight,” Tatum said.

Of course, this was not a grueling playoff series against a powerful opponent. It was a play-in game against a team that went 34-38 this season. The challenge now will become substantially greater, and it will arrive soon.

The Celtics’ reward for securing the No. 7 seed in the playoffs will be a first-round matchup against Kevin Durant, James Harden, Kyrie Irving, and the powerful Nets. Game 1 will be played on Saturday at 8 p.m. in Brooklyn.

“We know that challenge,” Celtics coach Brad Stevens said. “Those guys are the best of the best.”

In the waning moments of Tuesday’s game, the fans aware of this looming matchup started an expletive-laced chant directed at Irving, the impossibly talented point guard whose two-year Celtics tenure ended with a thud two seasons ago. Irving has yet to play in a game in front of fans at TD Garden since his departure, but that reunion is now imminent.

The Celtics lost all three of their games against Brooklyn this season, and often looked inferior as they did. Still, this chance is better than the alternative. If the Celtics had lost Tuesday, they would have faced an elimination game against the Pacers on Thursday.

Tatum didn’t need much help Tuesday, but Walker provided enough, pouring in 29 points. The health of Robert Williams is the primary concern now. The center returned Tuesday after missing five of the last six games because of turf toe.

He was a bit tentative, and did not look like the rim-running, shot-blocking force he has become. But he was still active and a good deterrent. Then with 40.6 seconds left in the second quarter he went up to block a Russell Westbrook attempt and landed awkwardly on the leg of Tatum. Williams was down for several minutes before limping to the locker room after aggravating his toe injury. He returned to start the second half but was clearly laboring. He checked out after just 71 seconds and did not return.

“[He’ll] just get treatment and see what happens,” Stevens said. “But, not enjoyable.”

The Celtics won despite shooting just 39.6 percent from the field, their first victory this season when connecting on less than 40 percent of their attempts. But they did enough to slow Washington’s fast-charging, relentless attack.

Kemba Walker and Washington's Bradley Beal collide in the second half of Tuesday's play-in game at TD Garden.Jim Davis/Globe Staff

Westbrook, whose scintillating run helped the Wizards reach this point, made just 6 of 18 shots and had 20 points and 14 rebounds. All-Star Bradley Beal had been slowed by a hamstring injury in recent weeks and appeared to be hampered in this game, too. He had 22 points on 10-of-25 shooting and was unable to create separation like he normally can.

The first half was bumpy for both teams. The Celtics missed most of their shots, the Wizards turned the ball over and could not hit a 3-pointer, and Washington’s 54-52 lead at the break felt mostly like a pause before one team decided it was time to strike.

And at the start of the third quarter, Tatum and Walker made it clear that it would be Boston. The duo opened the period with a 17-2 run of their own and combined to score the Celtics’ first 22 points of the quarter.

Walker took the baton at the start, drilling three 3-pointers over the first 2:35. And Tatum took it from there. He needed just over a minute to make a 16-footer, a 3-pointer, an alley-oop dunk, and another 3-pointer, quickly flipping the 2-point deficit into a 74-58 Boston lead.

“Jayson was special,” Walker said. “He was unbelievable. It ain’t new to me. I’ve been watching this guy put in this kind of work over the last year or two. So, I’m here for the ride. It’s fun. It’s always exciting to see him go off the way he goes off. We’re going to need that throughout this whole run.”

Jayson Tatum cashes in for two of his 50 points Tuesday against Washington.Jim Davis/Globe Staff

Whenever he stepped to the free throw line after that, he was serenaded with “MVP” chants. And when he drilled a 3-pointer with 5:32 left in the fourth quarter to give himself 48 points and the Celtics a 106-88 lead, there was a buzz in the Garden because it had become clear what would happen next. His 50th point came at the foul line, and the crowd erupted. He received a standing ovation when he checked out with a little less than two minutes left in the game.

“He’s a stud,” Celtics center Tristan Thompson said. “We know what he can do.”

At the start of this season, the Celtics never imagined they’d be relegated to a play-in game just to make the playoffs. Their goals were much grander. But they’re here now, and when Stevens gathered his players in the locker room after the game, he told them that paths to this point are different every year, and this season that has been filled with injuries, COVID-19 stoppages, and absences has been unlike any other. But they have made it now. They have a chance.

“It takes a lot of effort,” Stevens said. “It takes a lot of togetherness, and it takes staying together through tougher times.”