NASHVILLE, Tenn. -- Titans quarterback Marcus Mariota is "optimistic" he'll be able to start Sunday's game against the Indianapolis Colts after failing to finish the team's Week 16 win.

"I am just trying to get back and finding every way I can to be available," Mariota said Wednesday. "Of course I am optimistic. This is what it's about. We're playing for everything. I am doing everything I can day and night to get ready. You find every little treatment or rehab to get back out there. That's been my main focus."

Mariota suffered a stinger injury in Saturday's 25-16 win over Washington and said he felt numbness in his right side after the hit. He has since been cleared from the league's concussion protocol, but is listed on the team's injury report with a neck/foot injury.

Sunday's regular-season finale is a play-in game for the Titans and Colts as the winner will lock up a playoff spot. Tennessee has a 47.7 percent chance of making the postseason, according to ESPN's Football Power Index.

There is no deadline other than game day for Mariota to make a decision. He said it just comes down to whether or not he is comfortable playing.

Mariota was not on the field when the Titans practiced Wednesday, but coach Mike Vrabel said Mariota will continue to get treatment and he hopes his quarterback can return to practice Thursday.

Mariota wouldn't say whether the injury was related to the nerve injuries he encountered earlier this season. He also acknowledged that he had a nerve-related injury during his college career at Oregon.

If Mariota is unable to play, the Titans will again turn to Blaine Gabbert, who went 7-of-11 for 101 yards and a touchdown in relief of Mariota on Saturday.