Mariota is playing despite an injured elbow.
Marcus Mariota began the Titans' matchup with the Jaguars on the bench on Sunday, nursing an elbow injury that kept sidelined him during Week 2. But he was forced into action against Jacksonville in the first quarter, replacing the injured Blaine Gabbert.
Gabbert headed to the locker room after walking to the sidelines in the first quarter, entering concussion protocol.
Mariota finished 12 of 18 for 100 yards in place of Gabbert, who went 1 of 3 for eight yards before exiting the contest. The Titans beat the Jaguars 9-6 to improve to 2-1 on the season.