Five games into his return campaign, J.J. Watt suffered an injury that left him in tears and his team without its emotional leader and top defender.
The defensive end exited the Houston Texans' game against the Kansas City Chiefs on Sunday night after an apparent knee injury in the first quarter. He was helped off by trainers and later was carted to the team's locker room.
After being ruled out for the remainder of the game, he was later seen on crutches outside the locker room before being loaded onto an ambulance.
Watt underwent multiple back surgeries last year and missed all but three games in 2016.
Linebacker Whitney Mercilus was also ruled out after suffering a chest injury.