Blaine Gabbert left the Titans' game with Jacksonville in the first quarter and is being evaluated for a concussion after a helmet-to-helmet hit by defensive tackle Malik Jackson. Jackson was flagged on the play.
Gabbert walked off the field under his own power and went inside the medical tent for treatment. He then could be seen heading to the locker room.
Mariota missed last week's game because of an elbow injury that affects the velocity and spin of his passes.