Joel Embiid of the 76ers has surgery for appendicitis.

Philadelphia 76ers star center Joel Embiid is set to undergo emergency surgery in Houston on Thursday after being diagnosed with appendicitis just hours before the team was scheduled to compete against the Rockets in a crucial late regular-season matchup.

The team confirmed Embiid’s surgery shortly after he was unexpectedly listed on the injury report as out due to an illness ahead of Thursday’s contest—a game the Sixers must win to avoid the Eastern Conference play-in tournament next week.

It remains uncertain when Embiid will be able to return to the court.

Embiid, 32, is averaging 26.9 points and 7.7 rebounds across 38 games this season as he has gradually started to reclaim his MVP-caliber performance following a challenging season last year, during which he played only 19 ineffective games before being sidelined due to persistent issues with his left knee.

Philadelphia has faced a number of absences among its key players this season, with Paul George making his return just a couple of weeks ago from a 25-game NBA suspension.

As of Thursday’s games, the 76ers (43-36) are one game behind the sixth-place Toronto Raptors with three games left in the regular season as they aim to steer clear of the postseason play-in tournament.

The Sixers will then face Indiana on Friday and Milwaukee on Sunday—teams that are primarily focused on enhancing their draft lottery positioning.

However, the likelihood of avoiding the play-in tournament is further complicated by Embiid’s uncertain status. The play-in games next week are scheduled for either Tuesday (for the 7-8 matchup) or Wednesday (for the 9-10 matchup), followed by Friday (for the 8-9 matchup).