Luck ruled out of Thanksgiving game vs. Steelers with concussion

The Indianapolis Colts have made it official: Andrew Luck will not play in Thursday's game against the Pittsburgh Steelers due to a concussion.

Luck simply did not have enough time to clear the NFL's concussion protocol after picking up the head injury in Sunday's win over the Tennessee Titans.

Scott Tolzien will start in Luck's place, with Stephen Morris (whom the Colts added to the 53-man roster from the practice squad Wednesday) backing him up.

Tolzien will face a tall task at home in front of a national television audience of football fans stuffed with Thanksgiving dinner. The 5-5 Colts cannot afford to lose ground to the 6-4 Houston Texans in the race for the AFC South title.

The Colts also ruled out safety Clayton Geathers, who suffered a concussion Sunday as well. Cornerback Vontae Davis and wide receiver Donte Moncrief are listed as questionable.