Fremantle utility Adam McPhee is expected to miss 6-8 weeks after injuring his knee in Sunday's loss to West Coast at Patersons Stadium.

Scans taken today confirmed that McPhee had torn the posterior cruciate ligament in his left knee.

Meanwhile, Viv Michie will have his leg in a cast for 6-8 weeks after suffering a stress fracture in the navicular bone in his right foot.

The 19-year-old, who was Fremantle's second round selection (no. 44 overall) in the 2010 NAB AFL Draft, is yet to make his debut.