WEST COAST defender Mitch Brown appears to have suffered another serious knee injury after going down during the Eagles' season-opener against the Western Bulldogs.

Midway through the first quarter at Etihad Stadium on Saturday night, Brown was involved in a seemingly innocuous marking contest when his left knee appeared to give way. 

Play was held up for several minutes as Brown was assessed by trainers and taken from the field on a stretcher

It's a cruel blow for an Eagles line-up already missing key defenders – ex-skipper Darren Glass (retired), reigning best and fairest Eric Mackenzie (knee) and Will Schofield (ankle).

Brown ruptured the ACL in his left leg in 2008. Mid last year he suffered serious bone bruising and ankle damage in his right leg.

Brown's mishap meant teenage debutant Tom Lamb – the Eagles' substitute – was thrown into the fray earlier than expected.