Marcus Mariota's status has been closely monitored all week as he tries to overcome the elbow injury he suffered in the season opener against the Miami Dolphins and which kept him out of last week's win over the Houston Texans.
Tennessee still is hoping Mariota can regain the feel in his hand for the grip of the football as soon as possible, but the plan going into Sunday is to start Gabbert, sources said.
Mariota made progress in practice this past week while wearing a modified glove that had the index and middle fingers cut out of it to aid his grip, but coach Mike Vrabel said he will be cautious not to put his quarterback out there if he can't protect himself.
Gabbert took over for Mariota in the 27-20 loss to the Dolphins in Week 1, then led the Titans to a 20-17 win over the Texans. He is 24-for-42 with 234 yards passing over the first two games with a touchdown and an interception.
The Jaguars selected Gabbert with the 10th overall pick in the 2011 draft, and he spent three largely ineffective years in Jacksonville.