Philadelphia 76ers star Joel Embiid underwent a left knee procedure on Tuesday morning and will be reevaluated in approximately four weeks, the team announced.

The next few weeks of recovery and rehabilitation will be paramount, but there’s belief that the door remains open for Embiid’s return in the regular season, sources told ESPN.

Embiid, the reigning MVP, has sustained injuries to both knees in his career, and this one comes at an inopportune time for him and the Sixers. The All-Star center is leading the NBA in scoring with 35.3 points a game and was on pace to join Wilt Chamberlain as the only other player to average at least 35 points, 10 rebounds and 5 assists in a season. He’s also on pace to become only the second player (Chamberlain in 1961-62) to average at least one point per minute played.

The 76ers have lost six of their past seven games and have fallen to fifth in the Eastern Conference standings.