Collins was placed on injured reserve.
It's another blow to an offensive line that has dealt with injuries throughout the preseason. Minnesota lost left guard Nick Easton early in training camp after he underwent season-ending neck surgery on Aug. 9. Center Pat Elflein spent the entire preseason on the physically unable to perform list while recovering from offseason shoulder and ankle surgeries, and was inactive for the Vikings' Week 1 win over San Francisco.
Collins, a second-year lineman from TCU, played at both tackle spots and left guard during preseason games and was expected to serve as the Vikings' swing tackle. Rookie tackle Brian O'Neill and guard Danny Isidora are the remaining reserve linemen on the active roster.
Zimmer was asked about O'Neill taking on a bigger role in the wake of Collins' injury.
"AC's a good football player and we're going to miss him. We're going to continue to build depth, we're going to continue to push and I think O'Neill's getting better," Zimmer said.
With Collins out for the year, Minnesota may need to look to the free agent market to bolster its offensive line depth. The Vikings worked out centers Hroniss Grasu and Wesley Johnson and guard Bryan Witzmann last Friday, a source confirmed to ESPN.
Witzmann signed with the team on Monday.