THE HORROR news has continued at Carlton, with star forwards Jack Martin and Zac Fisher both set for extended periods on the sidelines with injuries sustained in last week's defeat to Collingwood.

Martin sustained a PCL injury to his knee in the dying stages of the clash, while Fisher has bone stress in his ankle, with both players likely to be sidelined for the next six weeks amid a crucial period for the winless club.

Both players had been among the standouts against the Pies, with Martin returning from a calf injury to kick three goals and Fisher again lively in his new attacking role to finish with one major from 16 disposals.

"Jack got a knock to his knee in the last contest of the game against Collingwood," the club's high-performance boss Andrew Russell said.

"It was your classic PCL mechanism, knee-on-knee. Initially, he wasn't too bad out of the game. But he's had some swelling and the MRI showed that he's got a low-grade PCL injury.

"Unfortunately, that's going to require that he's on the sidelines for around six weeks."

Fisher had enjoyed a full summer and had looked the most dangerous threat in the forward line throughout Carlton's first two games, but will again be sidelined for an extended period after he missed 10 matches last year due to a syndesmosis issue.

"Zac had some soreness late in the game against Collingwood," Russell said.

"He's got some bone stress in his ankle. It's a very, very unusual injury. It's the opposite to his syndesmosis ankle last year and we think at this stage that he's probably going to miss around six weeks of footy."

Martin and Fisher's injuries will likely see a recall for veteran forward Eddie Betts this week, while Jack Silvagni (shoulder) and Mitch McGovern (back) are also strong chances to return against Fremantle on Sunday.