Roethlisberger complained of headaches after practice on Wednesday and Thursday, despite passing all neurological tests this week and pronouncing himself fit to play.
Team doctors will test him today and tomorrow to see how he feels and if he'll be able to go, but all signs point to Big Ben not playing.
Dennis Dixon, who started the season as the No. 3 man, will be making the first NFL start of his career.
The Steelers plan to sign quarterback Tyler Palko from the practice squad today to their 53-man roster and he will back up Dixon tomorrow in Baltimore provided Roethlisberger does not suit up.
Palko's first practice with the Steelers came Thursday after he cleared CFL waivers and was signed to their practice squad. Veteran receiver Shaun McDonald will be released.