Jayson Tatum will miss Game 7 of the first-round series between the Boston Celtics and Philadelphia 76ers, the Celtics announced just hours before tip-off. Tatum left Game 6 after 29 minutes of playing time and did not return. He said after the game that he was “just a little stiff,” and was not initially worried about his status for Game 7.

However, Tatum popped up on the injury report on Saturday, getting listed as questionable with left knee stiffness. The Celtics have every reason to operate with an abundance of caution regarding Tatum’s health. He missed most of this season while recovering from a torn Achilles tendon suffered in last year’s postseason. He has been stellar since coming back, but there have been a number of serious injuries lately that started with players playing through smaller ones. Most notably, Tyrese Haliburton tore his Achilles tendon while playing Game 7 of the Finals with a calf injury. The Celtics are operating cautiously, so Tatum is sitting out.

“He just came in today with knee discomfort,” coach Joe Mazzulla said before the game (via MassLive). “The medical team and myself decided for him not to play.”

The Celtics fortunately developed quite a bit of experience playing without Tatum during the regular season. Boston opened the season with a 41-21 record before Tatum’s return in March. That included four regular-season games against the 76ers, two of which Boston won, and two of which the Celtics lost by a combined three points.

Tatum was averaging 23.3 points, 10.7 rebounds and 6.8 assists per game in the series before going down. Replacing that sort of production will be tricky. Jaylen Brown’s scoring has taken a dip in the postseason, and Derrick White, who was stellar for most of the season, has struggled mightily against Philadelphia. The Celtics traded Anfernee Simons at the deadline, costing themselves another shot-creator they could have used for a situation like this.

Still, the Celtics have never blown a 3-1 series in franchise history. They’ve beaten the 76ers in three different playoff series since drafting Tatum and Brown, and home teams tend to have a big advantage in Game 7s. The Celtics are perhaps as well-positioned to weather the loss of a superstar as any team in the NBA, but with their season hanging in the balance, they’re going to have to rely on their supporting cast to carry them through this winner-take-all game.