CALGARY - A fourth-quarter rally gave the Calgary Stampeders a 40-27 win over the visiting Saskatchewan Roughriders on Friday.

Down 12 points after three quarters, quarterback Bo Levi Mitchell threw a touchdown pass to Jock Sanders, Matt Walter scored his second major of the game on a two-yard scamper and defensive back Jamar Wall ran an interception back for a major.

Rene Paredes added an 18-yard field goal and the Roughriders also conceded a two-point safety in the quarter.

The Stampeders (14-2) already had first place in the West Division sewed up heading into the game. The division final Nov. 23 will be played in Calgary.

Saskatchewan (9-8) is playoff-bound and will be on the road in the post-season. The defending Grey Cup champions will either finish third in the West or be the crossover team in the East. The Roughriders lost their fifth in a row.

Drew Tate also scored for the Stampeders in front of an announced sellout of 35,400 at McMahon Stadium. Mitchell completed 21 of 31 pass attempts for 231 yards and one touchdown pass. The 24-year-old improved to 15-1 in career CFL starts.

Saskatchewan quarterback Kerry Joseph was 21-for-37 in passing for 322 yards and a pair of touchdown passes, but he was intercepted three times. It was the 42-year-old's second start for the Roughriders since coming out of retirement.

The Roughriders fell to 1-6 since regular starter Darian Durant tore a tendon in elbow Sept. 7 in a 30-24 win over Winnipeg. The 'Riders auditioned young pivots Tino Sunseri and Seth Doege before summoning Joseph, who quarterbacked them to a Grey Cup win in 2007.

Rob Bagg and Chris Getzlaf were Joseph's scoring targets. Linebacker Brian Peters added a defensive touchdown off an interception and had a team-high 10 tackles. Kicker Chris Milo contributed field goals from 32 and 33 yards.

The CFL's top two running backs didn't play Friday. Leading rusher Jon Cornish of the Stampeders was healing aches and pains, while No. 2 Anthony Allen of the Riders was scratched because of back pain.

Walter started at halfback in relief of Cornish and scored the second and third touchdowns of his career.

It was the first meeting at McMahon between the two teams since Saskatchewan upset Calgary 35-13 in last year's division final en route to the Grey Cup title. The Stampeders were the top team in the regular season with a 14-4 record.

The Roughriders enter a bye week and conclude the regular season at home against the Edmonton Eskimos. The Stampeders face Winnipeg next Saturday in the final home game and finish on the road against the B.C. Lions.