The Indianapolis Colts won't have Andrew Luck under center when they take on the Steelers on Thursday. The Colts ruled out the Pro Bowl quarterback Wednesday due to a concussion.
Luck was entered into the league's concussion protocol after showing symptoms on Monday and didn't practice this week.
Luck has started every game this season, completing 63 percent of his attempts for 2,827 yards with 19 touchdowns and eight interceptions.
Scott Tolzien will fill in for Luck and make his first start with the Colts. He started two games for the Packers in 2013.