Cassel broke his foot against the Saints during Week 3. He will not be eligible to return from IR until Week 13.
In three games this season, Cassel completed 41 of 71 passes for 425 yards, three touchdowns and four interceptions.
Rookie Teddy Bridgewater, the No. 32 pick in the 2014 draft, will be the team's new starter. He completed 12 of 20 passes for 150 yards with no touchdowns or interceptions against the Saints after Cassel left the game.
The Vikings are 1-2 on the season and will host the Atlanta Falcons on Sunday.
- Paul Palladino