Luck has not missed a game or snap because of an injury in his four seasons in the NFL. The last game he missed for an injury was the 2009 Sun Bowl, because of a broken finger while at Stanford.
A source told ESPN's Adam Schefter that Luck had an MRI earlier this week that revealed a bruise. A source told Schefter earlier Sunday that it was "trending" toward Luck being able to play.
Luck, who injured his shoulder against the Tennessee Titans in Week 3, was limited in practice Wednesday and Thursday. Coach Chuck Pagano said the quarterback was limited again Friday despite not being on the field during the time the media was allowed to watch practice.
ESPN.com's Mike Wells contributed to this report.