Ottawa Redblacks quarterback Thomas DeMarco will be out for the remainder of the season with an injury to his left ACL.
The Redblacks back-up suffered the injury in Sunday's game against the Calgary Stampeders after sustaining a hit from defensive lineman Junior Turner in the fourth quarter.
He was carted off teh field and did not return to the game.
DeMarco has completed 11 of 18 pass attempts for the Redblacks this season, his third in the CFL. His injury likely thrusts Danny O'Brien into the back-up role in Ottawa behind starter Henry Burris.
The 25-year-old played parts of 2012 and 2013 with the B.C. Lions.