The winner of Sunday's game advances to the West final Nov. 18 against the B.C Lions in Vancouver. The losers pack up their lockers for the season.
The Stampeders are favoured with a 12-6 record, which was good enough for second in both the division and the league. They're winners of four straight, while the Roughriders have dropped four in a row. Saskatchewan finished third in the West at 8-10.
Calgary has lost four playoff games to Saskatchewan over the last six seasons. Their most recent post-season meeting in 2010 was a major upset by Saskatchewan.
The Stampeders boasted a league-best 13-5 record and had won four straight heading into the West final. The Roughriders, 10-8, lost four of five to conclude the regular season.
With snow falling and a windchill of minus-24 C at kickoff, the Roughriders beat Calgary 20-16 and advanced to the Grey Cup for the second straight year.
While their post-season record against the Roughriders is unflattering, the Stampeders downplayed the past.
"This team is completely different than any other team that has played the Roughriders in the last few years," said Stampeder running back Jon Cornish.
"It's really just an opportunity for us to really show everybody that the past has nothing to do with what this team is capable of."
Added Stampeder receiver Nik Lewis: "I think we're the better team and I think we should win the game. Call us what you want but after tomorrow night, you can call us winners."
The Roughriders weren't as quick to dismiss their playoff success against the Stampeders. Defensive end Brent Hawkins said the upset two years ago can be inspirational Sunday.
"It's good to explain how that felt and what was actually going on that day for the guys who weren't here," Hawkins explained. "My roommate is Jay Alford and I said 'hey man, you don't understand what this is doing to be like. It's going to be cold, we're rivals.'
"I was telling him about how good it felt to beat Calgary here at their own place. They were heavily favoured. We definitely were the underdogs. It seems like it's kind of like that now, with this game."
The weather at McMahon won't be as challenging for players and spectators as it was in 2010.
The forecast for Sunday's game is sunny, but chilly with temperatures dropping from a forecasted high of -5 at kickoff towards -10.
The snowfall covering Calgary ended Saturday morning with no more accumulation expected prior to the game. The wind that sometimes whips mercilessly north-south through the stadium is projected to be 10 kilometres per hour out of the southwest.
Ticket sales numbers weren't available, but a Stampeder spokesman said 30,000 are expected at the game.
With no indoor practice facility, the Stampeders have trained outside in the elements since Oct. 26 when they beat the Hamilton Tiger-Cats at home in a near-whiteout. Subsequent wins in Alberta over B.C. and Edmonton were also in wintry conditions.
The Roughriders are no strangers to frost, but Calgary is claiming superior toughness when it comes to weather.
"The fact we've played in this for the last three or four weeks, I think it plays in our favour," Calgary long-snapper Randy Chevrier said.
"We do have a slight advantage. I wouldn't say it's a game-changer but we know how to operate in these types of conditions."
Another subplot is comparing the playoff experience of the two starting quarterbacks. Saskatchewan's Darian Durant led his team to the Grey Cup in both 2009 and 2010.
The Roughriders didn't make the post-season last year when Calgary's Drew Tate played the first half of a semifinal loss to Edmonton before he was replaced by Henry Burris.
Tate hasn't gone up against Saskatchewan's defence, nor have the Roughriders seen him in action since the pre-season. Tate's shoulder dislocation and subsequent surgery sidelined him for 14 games.
"It presents a challenge any time you haven't seen a guy, but Drew hasn't seen us either," Roughriders coach Corey Chamblin said. "Of course, we put some new things in because we know that he's new. We probably have more film on him than he will have on us.
"Drew is a runner, we know that, and a guy with a big arm. He hasn't played a lot of games this year, but I'm sure he'll be fired up and ready to go."
Chamblin was Calgary's defensive backs coach from 2008 to 2010. He wasn't surprised Stampeder coach and general manager John Hufnagel chose Tate over Kevin Glenn.
"I've been here before and I know that Drew is the guy," Chamblin said. "They've always loved Drew for awhile here. He's done some good things to grow in this organization so I figured it would be him."
Glenn and Tate shared quarterback duties the final two games of the regular season. Since Hufnagel announced Tuesday that Tate would get first snaps versus Saskatchewan, Cornish observed the quarterback taking charge.
"It really gave him a chance to step up and be the leader that he can be," Cornish said. "Having Drew's loud voice, it helps people realize what's on the line here. Having Drew's fire has been actually really helpful because I don't think a single person has even considered this being our last game."
Equal amounts Roughrider green will blend with Stampeder red in the stands. Calgary is full of Saskatchewan transplants and many from 'Rider Nation will make the journey for the game.
"I used to hate it when I was a Stamp," said Saskatchewan kicker Sandro DeAngelis, who was a Stampeder from 2005 to 2009.
"You'd run out of the tunnel and literally see a 50-50 split and it looked like a Christmas tree. Now that I'm on the other side of the rivalry, it's going to be a lot of fun."
Notes: Calgary went 2-1 versus Saskatchewan this season, including an overtime win . . . Durant is a career 2-0 in playoff starts versus Calgary . . . The Stampeders were 5-2 this season in games decided by four points or less . . . Calgary's home record was 7-2, while Saskatchewan was 3-6 on the road . . . The Stampeders are 9-0 this season when leading after three quarters.