Fremantle defender Luke McPharlin has a significant calf tear and will miss five weeks.

Senior coach Ross Lyon revealed the news on 6PR's Sports Today on Monday night.

McPharlin sat out the final quarter of Sunday's win over St Kilda after he had sustained the injury.

Lyon had hoped the 2012 All Australian would not miss significant time, but scans confirmed the 31-year-old would be sidelined for an extended period, beginning with Sunday's Carlton Mid Derby.

Lyon said Paul Duffield, who also has a calf injury, would miss the game against West Coast as well.

The Eagles will be without tough defender Beau Waters, who has a knee injury, and the suspended Patrick McGinnity