6:46 PM ET
Leonard appeared to suffer the injury while pursuing Bears receiver Darnell Mooney on an end-around play late in the second half. The linebacker was limping after the play but stayed in the game for the next snap before heading to the locker room.
Leonard later returned to the sideline before being officially ruled out. Zaire Franklin replaced Leonard at linebacker.
The leader of the Colts defense, Leonard led the NFL in tackles as a rookie with 163 in 2018. He also has 12 sacks and seven interceptions in his career.