The Indianapolis Colts will be facing off against the Pittsburgh Steelers at Week 12 for Thanksgiving Day. However, since Colts quarterback Andrew Luck was recently placed on concussion protocol, that means his backup Scott Tolzien will be leading the team on Thursday.

Luck most likely suffered the head injury during the Week 11 game against the Tennessee Titans. During the latter part of the game, he was sacked by Titans nose Tackle Austin Johnson. As the 314-pound athlete fell on top of him, Luck's helmet smacked on the ground.

As fans saw, Luck was still able to get up on his feet and even managed to finish the game, which the Colts won. He also appeared to be fine during his post-game interviews.

However, according to Colts coach Chuch Pagano, Luck later on started showing symptoms of a concussion. The same happened to safety Clayton Geathers, who also showed the same signs following the game against the Titans.

"Well after we were all done, both guys didn't feel right and both guys went in the training room and saw our docs," Pagano said. "Both were evaluated for concussions." 

Luck's exact status is not yet clear but given the number of steps involved in concussion protocol, he will most likely miss the upcoming game against the Steelers this week. Aside from the number of physical tests that he has to perform, he will still have to undergo evaluation conducted by an independent neurologist who will then determine if he will be allowed to play.

Since these tests can drag on for a number of days, there's a very big chance that Luck will not be the Colts on Thanksgiving Day, even if he gets cleared by doctors.

The Colts already know this, which is why they are reportedly planning on starting with Tolzien for the upcoming match, according to NFL.com. Tolzien has been in the NFL since 2011 after he was signed by the San Diego Chargers as an undrafted free agent.

Despite his long career in the league, Tolzien has little-to-no experience in being a starter. In fact, he only has two starts in his entire career and hasn't been on the field as a starter since 2013, back when he was still with the Green Bay Packers.