PITTSBURGH (AP) — Ben Roethlisberger's season doesn't appear to be over. Still, the Pittsburgh Steelers will have to move forward indefinitely without their star quarterback.

Coach Mike Tomlin said Monday Roethlisberger has a sprained medial collateral ligament in his left knee and there is no timetable for his return. Michael Vick will start Thursday night when the Steelers (2-1) host winless Baltimore (0-3).

Roethlisberger left in the third quarter of Sunday's 12-6 win over St. Louis after the knee bent awkwardly while getting sacked by Rams safety Mark Barron. An MRI taken late Sunday night revealed no major damage, leaving the door open for Roethlisberger to return at some point.

Vick completed 5 of 6 passes for 38 yards after Roethlisberger's departure.