Collingwood midfielder Harry Perryman will be sidelined for at least four weeks with a hamstring injury, while ruckman Darcy Cameron is in doubt for the bumper AFL clash with Geelong.
Cameron was cleared of structural damage to his injured ankle and remains a chance to take on the Cats at the MCG on Saturday night.
But he must get through Thursday's main training session before being named in the side.
Cameron was hurt in last week's draw with Hawthorn, as was Perryman, who had scans that confirmed a "moderate grade" hamstring injury.
The Magpies hope Perryman will be available to return in four to five weeks.
Steele Sidebottom had one of his hands stomped on in the Hawthorn game but was not included on the Pies' injury update on Tuesday.
Sidebottom is expected to play against Geelong alongside fellow veteran Scott Pendlebury, who returns after being rested and will equal the AFL games record.
Pendlebury will make his 432nd appearance, drawing level with retired North Melbourne champion Brent Harvey.
Meanwhile, Essendon recruit Brayden Fiorini is set to undergo back surgery, having last played in round two.
Melbourne forward Brody Mihocek will miss between three and five weeks with a hamstring injury sustained in his side's loss to Sydney last round.
"Unfortunately, Brody experienced pain after that tackle in the first quarter and scans have shown he suffered a moderate-grade hamstring strain," Demons high-performance boss Selwyn Griffith said.
"He was back in at the club today and has started to progress through our hamstring reconditioning protocol."
Melbourne midfielder Trent Rivers (knee) could return in Sunday's clash with West Coast at the MCG but Jake Melksham (ankle), Christian Salem (foot) and Xavier Lindsay (hip and groin) are still sidelined.
North Melbourne's George Wardlaw (illness) is expected to return against Sydney at Marvel Stadium on Saturday, but fellow midfielder Luke Davies-Uniacke is in doubt.
Davies-Uniacke had hamstring tightness in the Kangaroos' loss to Geelong last round.
"Pleasingly, Luke's presented well post-game and across the last 48 hours," North Melbourne head of performance Kevin White said.
"He was managed on Tuesday with extra recovery, but will look to train on Thursday and tick off high-end function to be available to play."
