Roethlisberger suffered a sprained throwing shoulder during the second quarter of Monday night's 16-13 overtime win against the Kansas City Chiefs.
With Roethlisberger out, veteran Byron Leftwich will start for the Steelers. Leftwich was 7 of 14 for 73 yards after replacing Roethlisberger on Monday night.
Before his exit, the two-time Pro Bowler completed 9 of 18 passes for 84 yards and a touchdown.
The Steelers aren't taking any chances with Roethlisberger, according to Glazer. The team is 6-3 and sits in second place in the AFC North. Even with the division-leading Ravens (7-2) on the schedule this week, Pittsburgh doesn't want to risk further injury to its franchise quarterback.
Six teams in the AFC have 6-3 records or better, so the Steelers would like to keep pace to try to earn a playoff spot.
The Steelers host the Ravens at 8:20 p.m. ET on Sunday.