The Tampa Bay Buccaneers could be losing a defensive captain for the rest of the 2018 season.

Linebacker Kwon Alexander left Sunday’s game against the Cleveland Browns with a knee injury, and the early fears are a torn ACL, per NFL Network’s Ian Rapoport:

Losing Alexander would be a huge blow for a Tampa Bay defense that looked like a much improved unit in the first half Sunday, only to struggle mightily in the second half without him in the lineup.

Alexander is in the final year of his rookie contract, making this the worst possible time for a serious injury.