Cornish is questionable for the game against the Argonauts — a rematch of the 2012 Grey Cup — with what head coach John Hufnagel called a thigh contusion.
The CFL's leading rusher last season and the No. 2 runner behind Saskatchewan's Kory Sheets this year didn't practise for a second straight day Wednesday.
"It I can't go, then I'll try and get straight. If I can go, I'll try and dominate," Cornish said.
But Cornish described the injury as one of "overuse" and not bruising. He ran for 175 yards and four touchdowns Aug. 9 in a 42-27 win over Saskatchewan, but was limited to 73 yards and one major in a 26-22 loss to the B.C. Lions last Saturday.
"I've recently restored a lot of range of motion to my leg that I haven't had for four years," Cornish explained. "My leg did more work than probably its done with that range of motion in the (Saskatchewan) game and then (I) played in the B.C. game. It didn't feel good in that game."
Calgary native Matt Walter will get the nod at halfback if Cornish can't play, Hufnagel said.
Calgary's depth at receiver is getting tested. Veteran slotback Nik Lewis is out for at least six games with a broken fibula he suffered in Vancouver. Maurice Price also won't play Friday because of an ankle injury.
Calgary (5-2) was already without receivers Joe West (shoulder), Johnny Forzani (ankle) and Chris Bauman (wrist) on the nine-game injured list.
So Montreal native Jabari Arthur will get a lot of work for the next month and a half during Lewis's absence. Former quarterback Brad Sinopoli of Peterborough, Ont., had five catches for 81 yards his first CFL game as a receiver July 12 and will fill in for Price.
It did not go well for Calgary's offence last week after Lewis went out in the second quarter following a tackle by B.C.'s Solomon Elimimian.
The Stampeders managed just two field goals in the second half as receivers dropped the ball seven times.
Stampeder quarterback Kevin Glenn went 22 for 38 for 199 yards in passing. Hufnagel blamed his team's inability to move the ball on his receivers.
"Probably one of the most disappointing games from our receivers that I've been associated with as a group," Hufnagel told the Calgary Herald earlier this week.
The coach and general manager was more moderate in his assessment Wednesday.
"I didn't call them out. I just explained what happened in the game," the head coach said. "I'd never seen a game with seven dropped passes before. Obviously our receivers have to do a better job of catching the football."
Toronto (5-2) would probably key on Cornish if he plays given Calgary's unsettled passing game. Cornish's absence would be all the better for the Argonaut defence, ranked No. 2 in the league.
"We're going to attack them as best as we can," Arthur said.
Marquay McDaniel led Calgary in receptions with seven for 75 yards in Vancouver. The slotback will probably again be a recurring target for Glenn with Lewis out.
"We've just got to go out there and know what we're doing each play, knowing your assignment and execute and just got to make the play when the ball comes your way," McDaniel said. "All year one guy's gone down and somebody's got to step up and fill that spot."
Arthur has dressed for every game and compiled 168 yards on 14 catches. He may not have the stocky Lewis's blocking talent, but at six foot four Arthur is half a foot taller than Lewis and thus offers more vertical.
"Nik has a very great skill set and we're probably going to miss it a little bit, but I think I also bring a different skill set to the table," Arthur said. "I think I'll still be able to make a few plays like Nik does for that position.
"I'm going to catch the ball if they throw it to me. That's what I'm going to do."