Boston Celtics center Al Horford has been placed on the NBA's concussion protocol after getting hit in the head during the team's practice on Monday. He will miss the Celtics' next two games against the Chicago Bulls on Wednesday and the Cleveland Cavaliers on Thursday.

The development was also confirmed by head coach Brad Stevens during his appearance on 98.5 The Sports Hub’s Zola & Bertrand on Wednesday:

“One of his teammates swiped at the ball and hit Al in the head. Right after, from everything I was told by Al and the training staff, he felt good Monday night. He came to practice Tuesday and was cleared, but once we started and he was moving around, after a few drills he felt pretty nauseous. He’ll be out the next two nights.”

Tyler Zeller is expected to see an uptick in his minutes in Horford's absence with the possibility of Amir Johnson seeing some playing time at the center position as well.

Horford is averaging 12.0 points, 5.2 rebounds and 4.7 assists in three games so far this season. If he doesn't suffer any further setbacks, he'll be able to rejoin the team when they go up against the Denver Nuggets on Sunday.