When Thanksgiving rolls around on Thursday, the Indianapolis Colts will be very thankful if Andrew Luck can play, because right now, it's not looking hopeful.

Colts coach Chuck Pagano announced on Monday that Luck is currently in concussion protocol, meaning that the quarterback would have to be cleared to play by Thursday or else he won't be allowed to suit up.

Luck suffered the concussion during Indy's 24-17 win over the Titans on Sunday, although it's not clear at what point in the game it happened. Pagano said he thought Luck was concussed in the fourth quarter. There is no shortage of theories on Twitter, either, from armchair concussion spotters.

According to the Colts website, Luck's status for Thursday's game against the Steelers is "up in the air." The Colts held a light walk-through on Monday and Luck didn't take part. The only two quarterbacks who suited up for the brief workout were Scott Tolzien and Stephen Morris, who's on the practice squad.

If Luck can't go, that means Tolzien would get the start. Tolzien is in his first season with the Colts after spending 2015 with the Packers. The 29-year-old has only thrown one pass since the beginning of the 2014 season.

Although it might seem unlikely that Luck would play, it's not impossible. Packers wide receiver Dante Adams played in a Thursday night game this year after being placed in concussion protocol on the Monday before the game.

If the past two years are any indication, the Colts are really going to need Luck because there's a good chance this game turns into a shootout. In 2014, the Colts lost a wild one to the Steelers 51-34. Indy also lost to the Steelers in 2015 in game where they got trounced 45-10. However, both of those games were played in Pittsburgh, while Thursday's game will be played at Lucas Oil Stadium in Indianapolis.

Luck has had the Colts on a roll over the past four weeks, with Indy winning three of its past four games. Thanks to that streak, the previously 2-4 Colts are now 5-5 and in the thick of the AFC South race.

A win in Thursday's game would be huge for both teams. The 5-5 Steelers are currently tied for first atop the AFC North.