The Stamps beat the Riders 42-27 in front of a sellout crowd of 35,637 fans at McMahon Stadium. The two West Division foes, which are tied atop the CFL standings with 5-1 records, will face each other once more this season on Oct. 26 in Calgary.
"It's always a great game when these two teams face off," said Saskatchewan quarterback Darian Durant, who completed 20-of-32 passes for 278 yards and three touchdowns. "It should be nothing less than that come October."
The Riders didn't surrender an offensive turnover in their first five games, but that all changed when running back Kory Sheets fumbled on Saskatchewan's second play from scrimmage in the opening minutes of the game.
Calgary defensive back Brandon Smith forced the fumble and the ball bounced off his body on the way out of bounds giving the Stamps possession deep in Saskatchewan territory.
Jon Cornish promptly ran for a 14-yard touchdown, his first of four in the game, to make the turnover a costly one for the Riders.
"We spotted them points," Sheets said. "We had crazy penalties. That's just not us. I fumbled the ball. We didn't play together as a team. You can't go out there and not play together and expect to win."
The Stamps led 26-6 after two quarters and the Calgary defence held Sheets to just eight yards rushing.
Sheets had a much better second half, especially in the third quarter when he broke off runs of 32, 26 and 21 yards as the Riders scored 13 straight points to pull within six.
"We executed in the second half," said Sheets, who finished with 133 yards rushing on 14 carries. "We didn't in the first. That's pretty much all it was."
Receiver Chris Getzlaf hauled in a pair of touchdown passes from Durant and finished the game with three catches for 43 yards.
"Getz is a great receiver," Durant said. "He made the plays. I just put the ball up to him."
Despite the loss, Saskatchewan coach Corey Chamblin gave his team credit for battling back to make it close in the second half.
"That's the biggest thing that I'm proud of with this team is they showed the fight and that's what I wanted to see," Chamblin said. "You come into a hornet's nest, they let it loose, but we came back. We fought back.
"They were the better team tonight, but it did show me that I still have a good football team."
Although he's disappointed with the loss, Durant said there were definitely some positives for the Riders to build off of heading into their next game against the Montreal Alouettes at home in Regina at Mosaic Stadium on Aug. 17.
"It was good for us to come out and make some plays," Durant said. "We still left a lot of plays out there though. I wish I could have had a couple throws back. That's just how the game goes.
"You've got to give Calgary a lot of credit, they made plays and we didn't."