Ben Roethlisberger will miss at least a month of action after suffering a knee injury in the Pittsburgh Steelers’ Week 3 game against the St. Louis Rams. The Steelers have scheduled an MRI on Roethlisberger’s knee for Monday and he will be re-evaluated.

ESPN reported a four-to-six-week timetable for recovery for Roethlisberger, who left with 5:35 remaining in the third quarter after being sacked by St. Louis safety Mark Barron. Roethlisberger went down after the play and was seen in crutches after the game. He was diagnosed with a sprained MCL in his left knee, but the injury did not include a tear of his ACL.

Veteran quarterback Michael Vick, who was signed in the 2015 offseason, filled in for Roethlisberger. The Steelers won the game, 12-6, with Roethlisberger finishing with 192 passing yards on 20 of 24 completions with an interception. Meanwhile, Vick completed five of his six pass attempts for 38 passing yards.

Steelers offensive lineman Ramon Foster criticized Barron’s hit as “kind of low,” and said he expected the league to take another look at the play. Meanwhile, Barron said the hit was accidental as he “stumbled a bit” on his way to hitting Roethlisberger’s knee.

The Steelers improved to 2-1 with the win. With Roethlisberger missing at least a month, the team will likely stick with Vick against the Baltimore Ravens, San Diego Chargers, Arizona Cardinals and Kansas City Chiefs, through Weeks 4 to 7.