CALGARY — After some optimism earlier in the week, Bo Levi Mitchell won't make his return to the lineup for the Calgary Stampeders against the Montreal Alouettes on Saturday.

Instead, Nick Arbuckle will start his seventh straight game at quarterback for the Stampeders (5-3) in place of Mitchell, who has missed the past six games with a tear in his pectoral muscle.

"Unfortunately, Bo had to take a step back," Calgary coach Dave Dickenson said of Mitchell, who practised on Tuesday but didn't throw on Wednesday or Thursday due to soreness.

Dickenson also revealed that there's no timetable for the return of last year's CFL outstanding player and Grey Cup MVP, and that Mitchell has been placed back on the six-game injured list.

"We just weren't able to get him practising and feeling good, but Nick does feel like he's ready to go, which is what we've been operating with the last six weeks anyways," said Dickenson, who added that the Alouettes (3-4) will pose a "big challenge" for Arbuckle and the Stamps.

"Nick's been playing good football, but we know we're going up against a really good opponent and hopefully our offence plays well. Montreal does a lot of good things on defence. They seem to be really locked in on what they're trying to accomplish."

Regardless of who is in at QB for Calgary, Montreal coach Khari Jones prepared his team to face a strong offensive unit.

"We knew whatever we got, we were going to get a quality club," Jones said. "Of course, Bo Levi Mitchell is as good as it gets in the league, but if we had to face him, we were going to be prepared for that.

"We think Arbuckle is doing a really good job over here as a young quarterback, so we knew that no matter who they showed up with, they were going to play quality football and we have to be ready for that."

Although he hasn't been spectacular in Mitchell's absence, Arbuckle has put up decent statistics while compiling a 4-2 record as a starter.

"It's a mindset that comes down from management to the coaching staff into the locker room that we just know whoever's on the field can get the job done and we know that we just have to execute and keep ourselves in the game," said Arbuckle, who has completed 143-of-201 passes for 1,733 yards to go with seven touchdown passes, five rushing TDs and five interceptions.

"Hopefully at the end of the games we have a chance to win it with a drive and we've been successful and we've had some mistakes where we haven't been able to finish the way we wanted to."

Looking to rebound from a 26-24 road loss they suffered to the Winnipeg Blue Bombers on Aug. 8, the Stamps received some good news this week when running back Don Jackson was cleared to play after missing the past six games with a concussion.

"We took the proper steps to make sure I'm getting on the field and I'm feeling confident and I'm ready to go," said Jackson, who needs just 28 rushing yards to reach 1,000 for his career.

"When I get the ball in my hands and I get the opportunity, I've got to make something happen. We've got a great quarterback in Nick Arbuckle, so we're excited for him to continue to lead the offence."

Meanwhile, the Alouettes will welcome back QB Vernon Adams Jr. to their lineup after he missed the team’s 17-10 loss at home last Friday to the Saskatchewan Roughriders with a concussion.

"He brings great work ethic to the team and he's playing good football," said Jones. "It's fun for me to see at this point in his career, with all the ups and downs, that's he's taking the reins of this football team and making it his own and that’s what you want out of a quarterback.”

Adams said that he’s "feeling good" after a solid week of practice.

"We're all hungry to get back to at least .500 and try to get back in the winning column," Adams said. "We know this is a great defence and a great offence with whoever's at quarterback. We just can't give them too many chances. I have to take care of the ball, try not to throw any interceptions and just get the athletes the ball and let them do the rest."

MONTREAL (3-4) AT CALGARY (5-3)

Saturday, McMahon Stadium

SOLID START — Stampeders DB Tre Roberson had a solid start to the season with five interception in Calgary's first three games, but hasn't been able to pick off a pass during his past five outings.

ROAD WOES — The Als will attempt to win back-to-back road games for the first time since the end of the 2016 season (a span of 21 games). The last time Montreal won in Calgary was when it beat the Roughriders 28-27 to win the 2009 Grey Cup. Montreal's last win over the Stamps in Calgary was on July 1, 2009. "I like the challenge of it," said Montreal coach Khari Jones in regards to the Als potentially snapping their nine-game losing streak at McMahon Stadium. "I want our guys to play teams at their best and see where we are as a football team, so I'm excited to see it."

SLOW STARTS — The Stamps have scored just 29 points in first quarters this season (only the Toronto Argonauts have scored fewer). In comparison, they had 64 points in the opening quarters in 2018 through their first eight games.

SHORTCHANGED — The Alouettes lost 17-10 last Friday to the Saskatchewan Roughriders in a weather-shortened game that was abandoned with 2:41 to play in the third quarter. It was the second such cancellation in CFL history after an October 1954 game in Vancouver between Saskatchewan and the B.C. Lions that was halted due to inclement weather.