The Facts: Mariota is not expected to start Sunday night against the Indianapolis Colts primarily because of a nerve condition caused by a "stinger," which has his overall playing status in jeopardy, sources familiar with his injury tell ESPN. Mariota is officially listed as questionable and reportedly will test his arm in pre-game warmups. But one source told ESPN that an independent spine specialist has warned the Titans that further damage will put Mariota's ability to throw the football at significant risk beyond this weekend.

Diehards Line: Blaine Gabbert is expected to start in Mariota's place, according to sources, against the Colts in a AFC South game in which the winner will advance to the playoffs and the loser will be eliminated. The Titans also signed free agent quarterback Austin Davis this week, and he likely will be the backup quarterback against the Colts. The Titans are hopeful that the nerve trauma will diminish with more rest and allow Mariota a chance to play in the postseason, a source told Mortensen. ... It's something we'll continue to watch going forward.