Jaguars defensive end Aaron Kampman tore the anterior cruciate ligament in his right knee during practice Thursday.
Kampman suffered the injury during a non-contact drill and will be placed on the injured reserve.
"It's a shame because he's a special young man in a lot of different ways, not only on the field but in the locker room, in the community," coach Jack Del Rio said.
Jacksonville signed Kampman to a four-year, $25 million contract in March.
Aaron Kampman Tears ACL In Practice