The move also signals the end to Christian Ponder's time as Minnesota's starter.
Cassel sparked the Vikings to their first win of the season in Week 4 against the Pittsburgh Steelers in place of Ponder, who was dealing with a fractured rib. After the bye week, Ponder returned to practice and has been deemed healthy to play, but Frazier is sticking with Cassel. Ponder will be the backup Sunday when Minnesota (1-3) hosts Carolina (1-3).
"We made a decision, really probably couple of days ago, when I was thinking about our quarterback situation and how we were going to handle it," Frazier said. "And now that we're done through this week and everything has kind of worked out from an injury standpoint, we can make a decision. … Matt Cassel is going to be our starting quarterback on Sunday. Christian's going to back him up."
Frazier said the team hasn't made a decision on the status of quarterback Josh Freeman, who was signed this week after being released by the Tampa Bay Buccaneers, but Freeman is likely to be inactive. The Vikings haven't made their third quarterback active in any game this season.
"We don't see him being able to play this ballgame yet, based on where we are and where he is with our offense," Frazier said.
Freeman will have the chance to start later in the year, but for now it's Cassel, who was 16 of 25 passing for 248 yards and two touchdowns in a 34-27 win against Pittsburgh.
"I've been focusing on it without really knowing but at the same time anticipating maybe this would happen," Cassel said, later adding: "It's exciting. That's why you come out here and you compete through OTAs and minicamp and all that stuff. This week I'll get another opportunity and I'm excited to get back on the field with these guys."
Frazier refused to name a starter earlier in the week, instead choosing to watch the full week of practices. But he confirmed that the decision had already been made about Cassel. Ponder spoke to the media Thursday and said he
had been told the plan, but deferred to Frazier on the announcement.
Cassel said the announcement wasn't official until Frazier told the media, but did say he got more repetitions in practice as the week went along. During the portions of practice open to the media, Cassel was first in the rotation of quarterbacks, followed by Ponder and Freeman.
A former starter with Kansas City and New England, Cassel said he isn't sure if he'll be given the chance to seize the starting job long-term and said he isn't thinking about the future right now.
"You know what? You never know in this league," Cassel said. "I wouldn't have guessed on Monday we'd have another quarterback in the room as well. You never know what's going to happen. But at the same time it's always about getting myself prepared and being accountable to my teammates, getting ready to go."
Frazier had maintained through the bye week that Ponder was still the team's starter if he was deemed healthy enough to play. Ponder had started 29 straight regular-season games before missing last week. However he had seven turnovers the first three weeks of the season and never seemed to develop into the franchise quarterback Minnesota hoped it would be when it spent the No. 12 overall pick on Ponder in the 2011 draft.
Ponder is 31st in the NFL with a 65.9 quarterback rating, 31st in yards (691 passing yards), 19th in completion percentage (59.0 percent) and had four total touchdowns to go with five interceptions and two lost fumbles.
Once the future at the position for Minnesota, Ponder is now behind Cassel, and eventually Freeman in the quarterback hierarchy for the Vikings.
"I think it's always tough when you make a change at quarterback," Frazier said. "You have to take a lot of factors into it when you're doing that. You don't make those decisions lightly and we didn't. We'll see how it plays out. But this is the start of this ball game, we'll see how Matt does. But we'll see how it plays out over time."
Frazier wouldn't commit to Cassel beyond starting Sunday and isn't sure when Freeman will be able to play as he tries to learn the team's offense.
"I think we need to sit back on Monday after the game and evaluate things and see where we are," Frazier said. "See how it goes."
Walsh questionable for Sunday: Kicker Blair Walsh is dealing with left hamstring tightness and wasn't out for the special teams portion of Friday's practice. Frazier said Thursday that Walsh felt a "twinge" and didn't finish practice.
Frazier said Walsh will be listed as questionable for Sunday's game. Frazier said the team wasn't looking to sign another kicker yet, but will have to check on Walsh again this weekend.
"We're going to list him as questionable just because of that tightness and not sure how he's going to be," Frazier said. "We need to see some things before the game. But he should be able to go. Just to err on the side of caution, we're going to list him as questionable for the game."
Frazier said rookie punter Jeff Locke would potentially be the replacement for Walsh in-game, if the situation arose.
"If that became the situation," Frazier said of locking filling in even in terms of field-goal attempts. "Now we're obviously hoping that doesn't become the situation, but yeah that would be Jeff as well."
Cook, Sanford and Ellison back: Cornerback Chris Cook (groin) and safety Jamarca Sanford (hamstring) practiced again Friday and both should return for Sunday's game after missing the last game against Pittsburgh. Both are listed as probable.
Frazier said tight end Rhett Ellison (knee), who is listed as questionable, should be able to play Sunday. Ellison has missed the past two games.