Travis Varcoe is out with a hamstring injury, heading several personnel issues for Collingwood ahead of their AFL blockbuster against arch-rivals Carlton.
The speedy defender limped off in the third term after being among their best players in Sunday's crucial win over Geelong.
"The scans verified that it is a slight strain, and he will certainly miss this week," Magpies football manager Geoff Walsh said.
"With hamstrings, it's more than likely that it could develop into two weeks.
"It's not a bad one, so we'll reassess things in seven to 10 days and see how well he is travelling."
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While Varcoe's injury is a blow, they have several prominent players in the selection frame.
Jordan De Goey has served his club-imposed penance and could return, while key defender Ben Reid was rested from the Cats match.
Rupert Wills, like De Goey, has shown good VFL form.
De Goey has played three games in the VFL as part of his punishment for lying to the club about a pre-season hand injury.
He initially told the club the injury happened while playing with his dog, but it quickly became apparent that De Goey was hurt in a bar fight.
De Goey boosted his hopes of a recall with 32 possessions on Saturday in Collingwood's VFL win over Sandringham, where Wills also impressed.
While the Magpies are coming off an impressive win over Geelong, they might have to make changes because next Saturday will be their third AFL match in 12 days.
Reid was rested from the Cats match because it was only five days after the Anzac Day loss to Essendon.
There will be more meaning than normal when Collingwood play Carlton on Saturday because it marks the Magpies' 125th birthday.
The Blues would love to spoil the party and they are coming off an upset win over Sydney.
