What is Jayson Tatum's injury? Why Celtics star isn't playing in Game 7 vs. 76ers

Jayson Tatum will miss Game 7 on Saturday night with what the Celtics are calling left knee stiffness. Tatum first appeared on the injury report early Saturday afternoon with a questionable tag, then was ruled out less than two hours before the start of Game 7.

"He came in today with knee discomfort," head coach Joe Mazzulla said before the game. "Back-of-the-knee stiffness. Day-to-day."

Mazzulla later implied that Tatum wanted to give it a try, but the team overruled him.

Tatum was seen on the Game 6 broadcast trying to loosen his left leg during a timeout, and he sat for most of the fourth quarter in the blowout loss.

After the game, Tatum downplayed the injury and said he planned on playing in Game 7. However, Tatum didn't appear to recover as expected, leading to him missing the contest.

Tatum played in just 16 games this season after recovering from surgery on his right Achilles. Tatum's return was a few weeks less than 10 months from when he suffered the Achilles injury in the second round of the NBA playoffs last year.

While this injury is to his left leg and his previous injury was to his right leg, it's possible that Tatum suffered the injury as a result of returning from such a serious rehab over the past year. Therefore, Boston is likely being overly cautious to make sure Tatum's injury doesn't turn into anything more significant.

Which Achilles did Jayson Tatum tear?

On May 12, 2025, Tatum tore his right Achilles in Game 4 of the second round in the NBA playoffs. That led to Tatum missing most of the 2025-26 season before returning on May 6.

Tatum's current injury is to his left leg, so it isn't a new injury to his surgically-repaired leg. instead, the injury may be due to him overcompensating on his left leg upon returning to action.