League sources said Tatum’s comeback would hinge on completing every stage of his rehab, no matter how menial or arduous, and that there would be no suggested timeline for that.
Jayson Tatum shares a moment with his son, Jayson “Deuce” Tatum Jr., before the start of the Mavericks game Friday.Matthew J. Lee/Globe Staff
Then just over a week ago, sources said, Tatum cleared the final hurdles related to his leg strength and his basketball work. He was told that once he was mentally ready, he could play in an NBA game.
Get Starting Point
That all led to Friday night’s game against the Mavericks, with Tatum walking onto the court with his left index finger in the air. The crowd reacted as if he had just hit a game-winning shot in the Finals.
“It’s been a long time coming just to get to this point,” Tatum said after registering 15 points, 12 rebounds, and 7 assists in this 120-100 win. “Nights and days, I dreamed about this moment and the anticipation, the crowd. It’s been 42½ weeks.”
Tatum’s start was imperfect. He said he was nervous, and moving too slow or too fast. He missed his first six shots, including an air-balled 3-pointer and a one-handed dunk attempt that was rejected by the rim. But coach Joe Mazzulla brushed off the sequence, pointing out that Tatum missed six shots in a row when he was an MVP candidate, too.
Regardless, the rut did not last.
Late in the second quarter Tatum converted a putback dunk — hanging on the rim briefly to ensure a soft landing — before drilling a 3-pointer, igniting a stretch in which he made five consecutive shots.
When he checked out with five minutes left in the fourth quarter, with Boston in control, he received a standing ovation from the crowd and a hug from Mazzulla.
“I thought he played with a free mind,” Mazzulla said. “I thought he played with a sense of gratitude, a sense of perspective. I thought he played with a sense of freedom, of just, ‘I’m here, I’ve accepted this, I’m grateful for this, and how can I continue to grow and get better, but also be myself?’ ”
For months, Tatum has remained an essential part of this franchise while also being forced to monitor it from a different space.
When the team practiced, he often completed his rehab in the weight room. When the team celebrated big moments on the court, he tried to remain engaged while wearing street clothes on the bench.
During a meeting Thursday, with his return inevitable, Tatum told his teammates there were times he felt lonely, but those feelings never lasted.
A Celtics fan welcomes back Jayson Tatum during first-quarter action Friday.Matthew J. Lee/Globe Staff
“I just expressed that being around as much as possible, going to games, being on the plane, really made me feel like I was still very much a part of the team,” Tatum said. “I really was just kind of telling everybody in the room that they all played a part in essentially getting me to this moment. And I was very thankful for that.”
Of course, the Celtics missed having one of the best basketball players in the world on the court with them, too. Few outside Boston’s locker room imagined that if Tatum came back this season, he would rejoin a title contender.
And on Friday, despite some predictable flaws, this group provided a reminder of what could be possible when it is whole.
“I know it’s been a difficult journey mentally and physically [for Tatum],” said Jaylen Brown, who has emerged as an MVP candidate. “To see him coming back is the start of his testimony and the start of his story arc to getting back to who he is and where he wants to be.”
There is a dry-erase board in Boston’s locker room that lists players’ pregame shooting times. And there was one notable addition Friday: “5:30—JT.” A good portion of TD Garden’s lower bowl was filled to watch Tatum complete his pregame workout hours before tipoff, with white No. 0 T-shirts draped over every seat.
About 90 minutes later, longtime public-address voice Eddie Palladino added something extra to Tatum’s starting lineup introduction.
After going 0 for 6 during his first two stints, including the missed dunk attempt that Brown said made him nervous, Tatum found a rhythm over the final few minutes of the second quarter. His two-handed putback dunk on a Payton Pritchard miss was followed by the step-back 3-pointer, with fans breaking into chants of “JT! JT!”
That flurry was part of an 11-2 Celtics run that gave them a 58-53 halftime lead. The cobwebs were gone.
At the start of the third quarter Tatum converted a driving layup and a midrange pull-up before draining a 3-pointer from the left corner, his fifth consecutive made shot. Then he found a cutting Brown for a layup to stretch Boston’s lead to 70-64.
Tatum had a chance to put an exclamation point on his night when Brown threw up an alley-oop on a fast break, but he was unable to get there for a dunk and missed the layup. He ensured there’d be no sour taste, however, when he drilled a 3-pointer on Boston’s next possession to stretch the lead to 106-87.
“It’s a very serious thing that happened that I had to overcome,” Tatum said. “And this was a huge step. I’ve still got a long way to go. But this was a really big step for me.”
Adam Himmelsbach can be reached at [email protected]. Follow him @adamhimmelsbach.
