Indianapolis Colts quarterback Andrew Luck (12) is tackled by Tennessee Titans defensive tackle Jurrell Casey (99) during the first half of an NFL football game in Indianapolis, Sunday, Nov. 20, 2016. (AP Photo/Darron Cummings)
INDIANAPOLIS (AP) Indianapolis Colts quarterback Andrew Luck is in the NFL's concussion protocol after complaining of concussion-like symptoms after a victory Sunday over Tennessee.
Coach Chuck Pagano says Monday he believes Luck's concussion occurred in the fourth quarter of the 24-17 win.
The Colts (5-5) host Pittsburgh on Thanksgiving night, leaving little time for Luck to recover.
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Indy's backup quarterback is the rarely used Scott Tolzien.
Pagano said safety Clayton Geathers also is in the concussion program.
Even with Luck healthy and playing pretty well this year, it's been a struggle. Indy needed fourth-quarter rallies to win its first two games and had to hold off opponents' comeback bids in each of the last three wins.
Last year, Luck missed nine games with multiple injuries, the last seven because of a lacerated kidney. To help keep him healthy this season, the Colts reduced his workload at practice. But he has been sacked a league-high 35 times.
Luck's 2015 injuries forced the Colts to rely on four additional quarterbacks to get through a season in which they finished 8-8 and missed the playoffs for the first time since 2011.
Tolzien has two career starts, both in 2013 when he replaced injured Green Bay quarterback Aaron Rodgers. He finished that season 55 of 90 with 717 yards, one touchdown and five interceptions. He hasn't thrown a pass since.
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