Brian Hoyer sustained a suspected knee ligament tear during the Cleveland Browns' 37-24 win over the Buffalo Bills last night.
The quarterback, who has been the AFC North side's starter for the last three games, left the clash in the first quarter.
The 27-year-old is due to undergo an MRI scan later today to determine the extend of the injury, which the team fears could include a torn ligament, according to NFL.com.
Fullback Chris Ogbonnaya also left the game with a concussion, while defensive lineman Desmond Bryant was taken to hospital after experiencing shortness of breath.
The win has left the Browns at the top of their division.