The Hamilton Tiger-Cats placed quarterback Zach Collaros on the six-game injured list Monday.
The CFL team confirmed the news on its official Twitter account.
Collaros has been out with head and back injuries after taking a hard hit from Edmonton Eskimos linebacker Odell Willis in a 28-24 loss on July 4. Collaros was flattened on the play after taking a helmet to the chin area.
The league fined Willis for the high hit.
Backups Jeremiah Masoli and Dan LeFevour have split time under centre for the 1-3 Tiger-Cats.
Collaros, a 25-year-old native of Steubenville, Ohio, was tabbed as the No. 1 quarterback after signing with Hamilton in the off-season. He has completed 23 of 41 passes for 212 yards, one touchdown, and two interceptions through two games this season.
Collaros spent his first two CFL seasons with the Toronto Argonauts.
Also Monday, the Tiger-Cats added defensive back Harold Mutobola and defensive end Kiante Tripp to their practice roster.