JAKE Lever will be missing from Narrm's backline for up to six weeks after undergoing knee surgery on an existing problem. 

The Demons were exploring the idea of Lever having an operation on his troublesome knee during the club's bye period after round 13, but the defender's concussion against West Coast brought forward those plans. 

MEDICAL ROOM Check out the full injury list

Lever was ruled out of the Demons' loss to the Eagles in the first quarter after copping an inadvertent head knock from Jack Darling. 

Demons high performance manager Selwyn Griffith said the uncertainty around Lever's recovery from concussion prompted the club to bring the operation forward. 

“Over the last month, Jake’s been managing a knee issue, which we had been looking at possibly intervening with over the bye to allow him the best opportunity to maximize his footy at the back end of the year.

“Obviously, with him now entering the concussion protocol and definitely missing a week, but then being uncertain about how quickly he would transition through that, we've made the decision to act on intervening on that knee.

“So, he had surgery today which has gone well. He'll now progress not only from a rehab of the knee, but also through the concussion protocol to hopefully back after the bye.”

Jake Bowey is also in some doubt to face the Saints on Sunday at the MCG after suffering a rolled ankle against the Eagles. Scans showed ligament damage but cleared the skilful small defender of a fracture, and he will face a fitness test later in the week. 

Jacob van Rooyen (concussion) is set to return against the Saints, provided he passes his final stages of recovery.