Favre was hurt in Sunday's victory over Buffalo when he was hit hard by the Bills' Arthur Moats during his first pass attempt -- an interception by Drayton Florence.
An MRI exam revealed a sprained sternoclavicular joint in Favre's throwing shoulder, and Frazier said his chances of appearing in the Vikings' next game against the New York Giants will depend on how he feels, the Minneapolis Star Tribune reported.
"From what I've been told, rest is probably key," Frazier told the newspaper. "That's going to be No. 1, and they'll do some exercises with him to help him as well … . It's just a matter of rest and then the rehab that they're going to put him through."
Favre has started an NFL-record 297 consecutive games.