The Toronto Argonauts lost their top signal caller early in Friday's game against the Ottawa Redblacks.
Quarterback Chad Kelly exited with an apparent lower-body injury after being tackled to the turf during a first-quarter drive.
The veteran signal-caller was later ruled out for the remainder of the contest, according to the Argonauts' head coach, Mike Miller.
Kelly was brought down by Redblacks defensive lineman Luigi Vilain while scrambling outside the pocket.
The 32-year-old QB threw the ball away, but was called for intentional grounding and walked off the field with a visible limp.
Nick Arbuckle took over under centre for the Argonauts.
Kelly was returning from a one-game absence, when he sat out against the B.C. Lions with a hand injury. On Friday, he wasn't credited with a single pass attempt due to the intentional grounding call.
He threw for 5,067 yards, 33 touchdowns and 24 interceptions in his first 15 games this year.
The Argos (9-7) are guaranteed to finish second in the CFL East and will host a division semifinal on Oct. 31.
The Redblacks are two losses away from becoming the first team in CFL history to finish 0-18.
