The Roughriders' Maurice Lloyd, top, and Fred Perry bring down Stampeders running back Joffrey Reynolds during the first quarter of the West semifinal Sunday in Calgary. ((Jeff McIntosh/Canadian Press) )

The Roughriders defence forced six turnovers and running back Kenton Keith scored a pair of key touchdowns to lead Saskatchewan to a come-from-behind 30-21 victoryat Calgaryin the CFL West division semifinal on Sunday.

Saskatchewan trailed 21-5 with under a minute to go in the first half before rattling off 25 unanswered points to score the upset over the Stampeders.

Afterquarterback Kerry Joseph and receiver Matt Dominguez connected on a 22-yard touchdown pass just before halftime, Keith broke off a career-high 76-yard touchdown run on the first play from scrimmage in the second half.

"Coach [Danny Barrett]told me, 'You're going to bust a big one,"' Keith said. "I tried to keep my head in the game. I was getting kind of down and the first play of the second half it happened."

A go-ahead 41-yard field goal by Luca Congi had Saskatchewan clinging to a two-point lead late in the fourth quarter whenKeith bulled his way to a 14-yard majorto get some breathing room for the Riders defence, which stifled Calgary on its last two possessions to secure the win.

Keith finished with 141 yards rushing on 16 carries and caught four passes for 28 yards.

James Johnson snatched a pair of interceptions, while fellow defensive back Eddie Davis picked off a pass and recorded nine tackles for Saskatchewan, which had a large and boisterous contingent of supporters among the 35,650 spectators at McMahon Stadium.

Miscues doom Stamps

TheRoughriders will now travel to Vancouver to take on the B.C. Lions in next Sunday's West championship (CBC, 4 p.m. ET).

"The last thing B.C. wanted to see was us come out of here," Riders defensive tackle Nate Davis said. "We took three out of four against them this year and some of them weren't real close."

The Toronto Argonauts, who defeated the Winnipeg Blue Bombersin the East semifinal, willgo on the road and play the Montreal Alouettes nextSunday in the East championship (CBC, 12:30 p.m. ET).

Sunday was a mistake-filled day for Calgary's star players. Quarterback Henry Burris lost a fumble and threwfour interceptions— including one on a desperation heave on the game's final play— while running back Joffrey Reynolds also coughed up a fumble and gained just 55 yards on the ground.

"It's pretty much a repeat of what happened last year," Burris said. "I can't have four turnovers without putting some points on the board."

Sandro DeAngelis, the league's top placekicer, missed a field goal and had another blocked.

Calgary takes early lead

DeAngelis opened the scoring for Calgary on its first possession by booting a 39-yard field goal.

Later in the opening quarter, the Riders looked to have a sure touchdown as Keith was wide open at the goal line, but the running back dropped Joseph's pass and Saskatchewan had to settle for a 13-yard Congi field goal.

After the Riders conceded a single, Reynolds gathered a short pass and looked on the verge of breaking a long run when he was stripped of the ball by safety Tristan Clovis. Linebacker Maurice Lloyd recovered the ball. Saskatchewan, though, failed to score off the turnover as Congi shanked a 43-yard field goal.

An early second-quarter safety put the Riders up 5-4 before Calgary's special teams unit scored the game's first touchdown. Markus Howell fielded a Congi punt on the numbers on the right side of the field, sliced through a sea of tacklers up the middle and raced into the end zone for a 57-yard major.

Immediately following the ensuing kickoff, the Stamps' Scott Coe forced a Joseph fumble and Terrence Patrick pounced on it. But, two plays later, Burris gave the ball right back by throwing his second interception of the game, this one to Johnson.

Riders storm back

Calgary extended its lead with a 25-yard DeAngelis field goal and Burris's one-yard touchdown plunge with a minute left in the half.

The Riders, though, did not go quietly into the break. Joseph engineered an eight-play drive that ended with him finding a wide-open Dominguez on the right side of the end zone for a 22-yard touchdown strike that cut the Stamps' lead to 21-12 at the half.

"That momentum swing was huge," Barrett said.

Saskatchewan again wasted no time in starting the second half as Keith took a handoff on the first play from scrimmage and scampered for a 76-yard touchdown.

After a single cut Calgary's lead to one, the Stampeders committed a pair of costly turnovers. With the ball on the Riders' 12-yard line, Burris ran a keeper and surged for a first down, but Saskatchewan defensive tackle Scott Schultz ripped the ball from his hands.

On the Stamps' next possession, Burris tossed an interception, his third of the day, to Davis along the left sideline.

Congi followed that up with a 41-yard field goal to give the Riders theirsecond lead of the day, and Joseph's 37-yard pass to Corey Grant set upKeith's insurance touchdown late in the final quarter.

With files from the Canadian Press