The Celtics’ coach, Joe Mazzulla, didn’t talk to his team any further about their first In-Season Tournament game. From his point of view, it was just one of 82 games.

It looked like his team played like it meant more.

Jaylen Brown scored 28 points and made five of his team’s 19 3-pointers as the Celtics beat the Nets 121–107 on Friday night.

The Celtics beat their first game in the tournament even though they had lost their last two games. Jayson Tatum scored 23 points and grabbed 10 boards.

After two straight losses, Boston’s bench played well and scored 37 points, with 15 coming from Sam Hauser and 13 from Payton Pritchard.

Mazzulla said that Pritchard “made a difference” all over the court.

Mazzulla said, “He changed the game for us.” “When you see how many points the bench players are getting, it’s easy to think they’re not doing much.” There are, however, many other things they do every day for us. We saw the other side of that tonight.

Walker IV scored 20 points and grabbed seven rebounds to lead the Nets. Trendon Watford scored 14 more points. Spencer Dinwiddie and Mikal Bridges both scored 12 points in the end. The Nets’ record in East Group C play dropped to 1-1.

Cam Johnson, who had been out with a pulled calf, played in his first game since the opener and scored 11 points on 4 of 13 shots.

“You can see that he changes the way we play,” Nets coach Jacque Vaughn said. “His ability to cover a lot of ground and guard different positions.” And that’s without having played a lot of minutes in games yet. He will continue to play, which will help him get rid of some of that rust.

In the third quarter, Brooklyn beat Boston 30-27, cutting an 18-point lead to nine points going into the fourth. But Boston went on an 18-6 run to start the last quarter and made it 111-90 with just under seven minutes left.

For the night, TD Garden’s signature parquet floor was replaced with a tournament-themed look required by the NBA. At midcourt, there was a picture of the new NBA Cup trophy next to the word “Boston” in green letters.

The change didn’t make the building less lively.

The Celtics led by as many as 17 points in the first 24 minutes because they pushed the pace and made 12 three-pointers. This team also took care of the ball, as they only turned it over twice.

It gave them a 66–54 lead at halfway.

Even though Brooklyn was short-staffed, it did its best to match Boston’s early run, and its bench scored 60 points on the night.

Ben Simmons missed his second game in a row because his hip hurt. Cam Thomas, who scored the most points, was also not playing because he is still healing from a sprained left ankle. For the Nets, this meant they didn’t have enough marked ball handlers, which made halfcourt play sometimes rough.

But 11 3-pointers in the first half kept them close.