BOSTON — Celtics star Jayson Tatum‘s belated birthday present to himself is a return to the game that was abruptly taken away from him last season.

Celtics coach Joe Mazzulla said Tatum will start the team’s Friday night home matchup with the Dallas Mavericks, in Tatum’s season debut almost 10 months after having surgery to repair a ruptured right Achilles tendon.

He was listed as questionable for the game Thursday before being upgraded to available on Friday afternoon. Tatum had been listed as sidelined and undergoing rehabilitation for the injury he suffered during Game 4 of Boston’s Eastern Conference semifinal loss to the New York Knicks last May.

Tatum, who turned 28 this week, previously indicated his return to the court would be for a home game. That time has apparently arrived.

“We always knew he was coming back this year,” Mazzulla said Friday. “I think I knew that when he decided to have surgery within 16 hours … whatever the case was.”

“I mean, it wasn’t a thousand percent sure,” Mazzulla added, “but I knew it was going to do everything possible to be in position to make a decision to come back.”

The Celtics (41-21) have 20 games remaining in the regular season, including 11 at TD Garden. Boston is currently in second place in the East standings.

After Friday’s home game against the Mavericks, the Celtics go on the road for three straight against playoff contenders: Cleveland on Sunday, San Antonio on Tuesday and Oklahoma City on Thursday.

The typical rehabilitation window to return to basketball action following Achilles tendon surgery is between nine and 12 months.

Tatum, who had surgery on May 13, is making his return to the court after 298 days.

Though Mazzulla said he had “no idea” if Tatum will be on a minutes restriction, some form of load management plan might be expected. However, Boston plays its next 12 games without any back-to-backs on the docket; the next one is March 29 and 30. That should allow Tatum a chance to get some consistent reps on the court and gradually build himself up ahead of a playoff push in which the Celtics will once again be seen as a favorite to emerge from the Eastern Conference.

He’s been clear since the start of his rehab process that his intention was to try to return to the court as the same player who was a catalyst during Boston’s 2024 NBA championship run and who has earned five All-NBA and eight All-Star selections during his previous eight seasons.

“I didn’t come back to be no role player, Doc,” Tatum said weeks after the surgery to his physician during a checkup that was chronicled in the recently released documentary “The Quiet Work,” which followed his rehab process.

Celtics forward Sam Hauser said Tatum’s drive to return to action has been evident throughout the season, from his daily workouts to travelling with the team on road trips while not missing a beat in his rehab process.

“It speaks volumes to how much he loves the game of basketball. He has been out roughly 10 months and him willing to come back on every single trip,” Hauser told reporters following the Celtics’ shootaround Friday morning. “He wants to be part of this.”

When Tatum went down with his injury last season, his thoughts quickly pivoted away from the devastation he felt for himself and what would soon be the end of his team’s bid to repeat as NBA champions.

He made the decision almost immediately to begin turning the page and opted to have surgery the very next day.

His return wouldn’t be far beyond the recovery time it took for Naismith Basketball Hall of Famer Dominique Wilkins to recover from his Achilles tendon rupture. Wilkins returned at age 33 after 283 days to play in the 1992-93 season. He went on to appear in 71 regular-season games that year, averaging 29.9 points per game and being named to the All-Star team.

Tatum’s childhood idol, Kobe Bryant, made it back to the court after about eight months, but was hampered by subsequent injuries.

Tatum is in the first season of the five-year, $314 million extension he signed in 2024.

Information from ESPN’s Jamal Collier, Shams Charania and The Associated Press was used in this report.