A Green Bay Packers defense that has not performed up to expectations in the first three weeks of the year will be without two key starters, end Vonnie Holliday and safety Antuan Edwards, for an extended period.

An MRI exam of what was initially believed to be a strain revealed Monday that Holliday actually suffered a torn pectoral muscle in Sunday's win over the Detroit Lions. Coach Mike Sherman said Monday that Holliday, one of the mainstays of the Green Bay defensive front, will miss at least 6-8 weeks.

According to ESPN.com's John Clayton, two New York doctors confirmed Thursday the Packers' diagnosis that Holliday won't need surgery. The confirmation by doctors David Alchek and Gerard Varlottta is good news for Green Bay and Holliday. Had Holliday needed surgery, he would have been lost for the season.

Sherman will consider moving starter Joe Johnson or third-down specialist Kabeer Gbaja-Biamila into Holliday's "power end" position and also noted rookie Aaron Kampman, a fifth-round draft choice, will now see extended playing time.

"Obviously, missing a player of Vonnie's magnitude is significant, but I feel confident with the way we're going to handle this," Sherman said.

Green Bay officials for weeks have been discussing a contract extension for Holliday but had not made much progress toward a new deal. The fifth-year veteran, a first-round pick in 1998, is a staunch defender versus the run.

Edwards, who inherited the starting strong safety spot when LeRoy Butler retired, suffered a fractured forearm at Detroit. It does not appear that the injury will require surgery, and the insertion of a plate to promote healing, but the team's 1999 first-rounder will miss 3-4 weeks.

Len Pasquarelli is a senior writer for ESPN.com.