Collaros was 4-of-10 passing for 106 yards with a TD and two interceptions prior to being hurt. He underwent concussion protocol after leaving the game.
Canadian Brandon Bridge replaced Collaros and was 13-of-22 passing for 145 yards with an interception while rushing four times for 27 yards.
Acquired in the off-season from Hamilton, Collaros was 18-of-25 passing for 203 yards and one touchdown in Saskatchewan's season-opening 27-19 win over Toronto.
Collaros missed three games with a head injury in 2016 and was sidelined two years earlier due to a concussion.
The Roughriders (1-1) host the Montreal Alouettes (0-2) on Saturday night.
ACTION JACKSON: It's been quite the CFL debut for Don Jackson.
The Calgary Stampeders running back has led the CFL in rushing in each of the first two weeks, accumulating 210 yards. Not only does that work out to over 100 yards per game, the first-year CFL player is also averaging a sparkling 10 yards per rushing attempt.
The five-foot-10, 202-pound Jackson combines with sophomore Terry Williams to give Calgary a solid two-headed rushing attack. Williams 5-9, 209-pounds, has run for 103 yards on 19 carries (5.4-yard average) but also had a 102-yard punt return for a TD in the Stampeders' lopsided 41-7 Grey Cup rematch win over the Toronto Argonauts on Saturday night.
"I told you we had a good running back, and I knew we'd have a good running game,'' Stampeders head coach Dave Dickenson said after Saturday's win. "We're a balanced team that likes to switch it up and make sure our offensive linemen are firing off the ball and Don has looked the part and done well.''
Canadian Jerome Messam registered consecutive 1,000-yard seasons with Calgary (2016-17) before signing with Saskatchewan in the off-season.
Jackson signed with Calgary in May after spending time with the NFL's Green Bay Packers. Canadian football is predominantly a passing game but the longer, wider field can potentially present big running lanes for backs.
Jackson finished with 123 yards rushing on 12 carries (13.7-yard average) against Toronto while Williams had 70 yards on 12 attempts (5.8 yards).
After he ripped off a 70-yard run, Jackson was reminded of the first lesson he learned in training camp.
"Get in shape, man,'' Jackson said with a chuckle. "The long run I had I was definitely beating myself up like, 'I've got to get into even better shape to where we can pull those things out no matter what the situation is.'
"It (100-yard game) is a blessing for sure. All I know is we've got a talented group of receivers and a talented offensive line. And when Bo (quarterback Bo Levi Mitchell) does his thing like he does, it's hard to play the run the way you want.''
Williams appeared in five games with Calgary last season, starting one. On Sept. 29, he ran for 156 yards and three TDs in a 59-11 home win over Montreal, earning CFL player-of-the-week honours.
Mitchell, the 2016 CFL MVP, was nearly flawless Saturday night, completing 20-of-22 passes for 324 yards and three TDs.
"We've got some weapons out there and we don't want to get complacent,'' Mitchell said. "But I am proud of Terry and Don with everything they're doing right now but they'll tell you it has a lot to do with what (offensive linemen) are doing.
"It doesn't allow teams to drop nine and play pass first and try to react to the run like they've done to us the last couple years. They've got to respect those guys and try to make plays on them and when they do we need to make plays behind them.''
STREVELER IMPRESSES: Rookie quarterback Chris Streveler completed 22-of-28 passes for 246 yards and three TDs in Winnipeg's 59-10 win over the Montreal Alouettes on Friday night. Streveler also had a team-high 98 yards rushing with a touchdown.
The 23-year-old was 15-of-28 passing for 178 yards and three TDs with two interceptions in his CFL debut, a 33-30 loss to the Edmonton Eskimos. He also ran seven times for 30 yards.
Streveler sports a solid 66.1 per cent completion average and has a league-high six TD passes with incumbent Matt Nichols (knee) sidelined.
MANZIEL WAITS: Former Heisman Trophy winner Johnny Manziel remained on the sidelines for Hamilton's two opening games of the season because of the play of incumbent starting QB Jeremiah Masoli.
Masoli has completed 44-of-65 passes (67.7 per cent) for 676 yards with four TDs and two interceptions for Hamilton (1-1). Masoli is second to Edmonton's Mike Reilly (694 yards) in CFL passing and has 71 yards rushing and a TD on nine carries (7.9-yard average)
Manziel, 25, signed with Hamilton on the eve of training camp. He's back playing pro football after being released in March 2016 by the Cleveland Browns, who selected Manziel in the first round, No. 22 overall, of the '14 NFL draft.
THIS 'N THAT: Quarterback Kenny Hill, who succeeded Manziel as the starter at Texas A&M, joined the Montreal Alouettes practice roster Monday. Hill spent two seasons at Texas A&M before transferring to Texas Christian University. His father, Ken, is a former Montreal Expos pitcher.