Boston Celtics All-Star point guard Kemba Walker recently received a stem cell injection in his left knee and will miss the start of the 2020-21 season after being put on a 12-week strengthening program, according to the team.

Walker is projected to return to on-court activities in early December and will await further updates regarding his situation in the first week of January.

The guard was hindered by his knee issues in the bubble, but the injury goes back further to before the 2020 All-Star Game. Walker was then supposed to be on a minutes restriction for the exhibition in Chicago, but he wound up playing a lot down the stretch in a close game and then got his knee drained soon after. It has been a lingering problem ever since.

The former UConn standout is heading into his second campaign in Boston after spending the first eight seasons of his career in Charlotte. Kemba Walker averaged 20.4 points, 3.9 rebounds, and 4.8 assists in 56 appearances to snag his fourth All-Star selection.

The Celtics finished with the third seed in the Eastern Conference with a 48-24 record. However, the team ran out of gas and fell short against the Miami Heat in the Eastern Conference Finals in six games.

Jayson Tatum took over as Boston's main man this past season, so that doesn't change with Walker sidelined. However, this only means more of a load for returning players Jaylen Brown and Marcus Smart, especially with Gordon Hayward gone. Furthermore, the Celtics' offseason acquisition of Jeff Teague looms even more important now that he's set to take over a lot of minutes at point guard.

In addition to Kemba Walker's injury, Romeo Langford is still recovering from wrist surgery. Tristan Thompson will be limited to start camp because of a hamstring strain suffered in an offseason workout.