Up a touchdown at halftime July 5 in Regina, they didn't score again while the Saskatchewan Roughriders churned out 22 points en route to victory.
When the Roughriders threatened to come from behind again Friday, the Stampeders preserved a 42-27 win on a tide-turning defensive play and offence from their big guns in the fourth quarter.
Saskatchewan lost for the first time this season, putting both teams at 5-1 atop both the CFL standings and the West Division standings.
"The one biggest thing we emphasized was finish because we didn't do that last time and I think we did it tonight," Stampeders quarterback Kevin Glenn said.
"The biggest thing was staying together as a team and having each other's back because we knew it was going to be a hard-fought game. They were undefeated for a reason."
Calgary running back Jon Cornish had a torrid night with four touchdowns, 175 rushing yards and another 20 receiving yards.
Saskatchewan counterpart Kory Sheets was held to just eight yards in the first half before the CFL's leading rusher strung together his trademark rumbles in the second. Sheets finished with 133 yards on 14 carries.
Calgary led 26-7 at halftime, but the Roughriders scored 13 unanswered points in the third quarter.
Demonte Bolden halted Saskatchewan's momentum by sacking quarterback Darian Durant in the end zone for a point in the fourth. Glenn then threw a 25-yard touchdown pass to Nik Lewis and Cornish scored his fourth major of the night on a one-yard dive.
"Saskatchewan is a great team and they proved it in the second half," Cornish said. "They have probably the most explosive offence I've seen in my seven years in the CFL.
"They can put up 100 yards in 10 seconds so it's really good we got this win against them, but it's going to be tough sledding against them the next game."
Calgary and Saskatchewan are 1-1 against each other and will decide the season series Oct. 26 in Calgary.
Calgary kicker Rene Paredes extended his CFL record for consecutive field goals to 36 with kicks from 30 and 27 yards.
Glenn was Calgary's starter instead of an injured Drew Tate, with backup Bo Levi Mitchell spelling Glenn on short-yardage situations. Glenn completed 21-of-28 pass attempts for 218 yards and one touchdown.
Durant returned to Saskatchewan's lineup after sitting out a game with an ankle injury. The veteran threw a pair of touchdown passes to Chris Getzlaf and another to Jock Sanders in front of an announced sellout of 35,637 wearing both Roughrider green and Stampeder red.
"We came into this game thinking we were on equal footing with Saskatchewan, but we had the advantage of being at home," Cornish said. 'People always say Saskatchewan (fans) always fills up the stands, but I saw a lot of Calgarian fans here today."
Durant was 20-for-32 in passing for 279 yards. Roughrider kicker Chris Milo kicked field goals from 28 and 13 yards.
"We knew coming out of the locker room at halftime we would have to make some hay," Calgary coach John Hufnagel said. "We didn't. They did, but we were able to seize the momentum back and the defence came up with a big safety.
"We took the ensuing kickoff and marched it down for a touchdown, so that was a big nine points in that football game."
Calgary dominated the first half by holding the CFL's leading offence to 135 yards, while Cornish ran for 115 and three touchdowns.
"Whenever you get behind on a good team, it’s always hard to make up ground," Durant said. "They had a great game plan. Their rushers and tacklers were really good tonight and we weren't able to make up the ground.
Cornish made the most of a gap created by his offensive linemen and raced 32 yards to score at 12:54 of the second quarter. Paredes gave the hosts a 19-point cushion before halftime with his second field goal of the game.
The Stamps led 13-0 after the first quarter on two Cornish touchdowns. Paredes padded the lead to 16-0 before the Roughriders countered in the second quarter. Durant marched the visitors 75 yards and finished the drive with a 20-yard pass to Getzlaf at 5:04.
Cornish's second TD of the opening quarter was a two-yard dash off a Mitchell handoff at 8:55.
The Stampeders turned Saskatchewan's first offensive fumble of the season into a major. On Saskatchewan's opening drive, the football squirted out of bounds when Brandon Smith brought Sheets down near the sideline.
Hufnagel's challenge overturned the initial ruling that Sheets was the last to touch the ball. Cornish's 14-yard run on the next play and a convert from Paredes put Calgary up 7-0 at 2:42.
The Stampeders are on the road against the B.C. Lions (4-2) next week, while the Roughriders host the struggling Montreal Alouettes (2-4).