Boston Celtics All-Star guard Kyrie Irving is sitting out Monday night’s game against the Bulls because of a sore left knee.

Coach Brad Stevens says Irving aggravated the knee during Saturday’s loss to Houston. He felt a little better the following day but was still sore on Monday.

Acquired from Cleveland in the offseason deal that sent Isaiah Thomas to the Cavaliers, Irving is averaging 24.8 points in 58 games. He has missed time this season because of a bruised quadriceps, a sore shoulder and a facial fracture.

The Celtics were second behind Toronto in the Eastern Conference at 44-20 entering Monday’s game.