BOSTON — Boston Celtics rookie Jayson Tatum showed right away in the preseason that he was willing, and able, to find his offense amid a lineup of stars.

Over the past two games, with multiple stars out of action, he has shown a willingness and ability to be the team’s closer offensively when the game has been on the line.

After he scored 16 points, including two big shots in the final three minutes, of Friday night’s 90-87 victory against the Charlotte Hornets, he was back at it Sunday afternoon at TD Garden as his acrobatic drive and finish with the shot clock winding down accounted for the final Celtics points as they extended their win streak to 12 with a 95-94 triumph against the Toronto Raptors.

“I just think it’s instinct,” he said. “The bench does a great job of letting us know how much time is on the shot clock when it’s running down like that.”

While the Celtics didn’t need to score again to win, the game was far from over with 1:26 left after Tatum’s highlight basket made it a 95-90 game. The Raptors scored the next four before Tatum grabbed a rebound with 13.4 seconds on the clock. But the rookie was whistled for an offensive foul, which stood up on video review, and he had to go back to playing defense for one last stop.

“It’s basketball,” he said. “You’re going to make mistakes. You can’t think about what just happened. They’re not going to change the call. You just have to look forward to the next play – especially when there is 15 seconds left on the clock.”

After Jaylen Brown contested DeMar DeRozan’s potential winning shot into a miss, Tatum helped keep the Raptors from a buzzer-beating chance on the offensive glass as the clock hit all zeros.

“We just are always fighting until the buzzer goes off,” he said. “We had a turnover at the end. I had an offensive foul. We had to fight through some things. But guys still fought.”

With Gordon Hayward potentially gone for the season, Tatum has stepped into the starting lineup. Then with Al Horford out two games with a concussion, before returning Sunday, and Kyrie Irving missing Sunday’s game with a facial fracture, Tatum has stepped into a key spot when it comes to making plays with the game on the line.

“He’s always been a guy that’s been wired to make plays and to score the ball,” Celtics Coach Brad Stevens said. “So it’s not a huge surprise that he feels comfortable in those moments.

“In the last couple of games, and specifically Friday night, we really needed him to make those plays. (Sunday), he was playing more against closeouts because other people were drawing the attention, instead of just isolation plays. And he took advantage of that.”

Tatum finished with 13 points and seven rebounds, but scored six of those points on 3-of-4 shooting in the fourth quarter.

Stevens said before Sunday’s game that Irving had not been diagnosed with a concussion – that he knew of – and was being fitted for a facemask that will allow him to play as the small fracture on his cheek heals. Stevens said he was not sure if Irving will be available for the team’s game in Brooklyn on Tuesday.

The team will, once again, rely on film study and Tuesday’s pregame walkthrough to take the place of a typical practice before playing Brooklyn. The Celtics have not had an official full team practice since Oct. 23.

“The one thing that gets overshadowed there is that film is huge,” Stevens said. “Individual and small group work is huge. These walkthroughs are practices for us. We get here at 3:15 before the game. We get out and we do a real warm-up. We did a real 40 minutes on the court. That’s when we think is best to use the time right now.”