Jetta will go under the knife on Tuesday after scans revealed the important defender had suffered a significant tear in the lateral meniscus in his left knee.

The Demons say Jetta had an "incident" during the second quarter of Saturday's loss to St Kilda, although the 29-year-old played out the game.

Questions are certain to be asked about the wisdom of the Demons playing Jetta in that game given he had missed the previous week with soreness in the same knee.

"This surgery will happen tomorrow, and we expect Neville to miss an extended period of time - most likely eight to 10 weeks," Demons football boss Josh Mahoney said on Monday.

"This is unfortunate for Neville and the backline but it provides an opportunity for some other guys to step up, and he will continue to lead from the sidelines."

Melbourne also opted to bring back Jordan Lewis for the game against St Kilda without time in the VFL and the veteran visibly struggled.

The Demons sit second-last on the ladder with one win from five games, having played in the preliminary final last season.

The club received some better injury news over the weekend with co-captain Jack Viney cleared to face Richmond on Anzac Eve after having scans on his hand.

Australian Associated Press