COLLINGWOOD will be without key forward Mason Cox for its clash with Carlton on Saturday afternoon, with the 211cm behemoth to miss again with an ankle injury.

His absence will delay the call the Magpies' selection committee will have to make on whether to dump veteran Ben Reid or keep him in and line-up with three talls in attack, alongside Brody Mihocek.

Reid, 30, impressed in his first game in almost a year after battling soft-tissue issues, while his form wasn't compelling enough to break into a side that made last year's Grand Final.

He booted 1.4 in the Pies' dominant win over Port Adelaide last week.

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Collingwood coach Nathan Buckley told Melbourne radio station SEN Cox would have to wait.

"He's another week away at least," Buckley said.

"He's a big fella. There's a lot of load through that lower leg so we'll give him a bit more time."

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Taylor Adams will be an enforced out, set to miss a month with a left adductor strain.

Meanwhile, hard-running wingman Chris Mayne could be on the brink of a stunning return from a back fracture, assuming he passes a fitness test, according to Magpies football manager Geoff Walsh.

"We're hopeful that his training session tomorrow (Thursday) will give him a green light to put his hand up for selection," Walsh told collingwoodfc.com.au. 

"He's recovered remarkably quickly after a pretty serious back injury but his last 10 days to a fortnight, he's really come on. If he can train strongly tomorrow, then he'll certainly give the match committee something to think about."

Luckless defender Matthew Scharenberg has joined in with the main group and is closing in on a return from a third knee reconstruction, the second to his left side.

"There's probably three-to-four weeks of full training and conditioning that we'll get into him but the good news is he's strongly on track to resume about the time that we said he would (five weeks away)," Walsh said.

Big-bodied onballer Brayden Sier should be right to resume this week from a toe complaint.

Backman Flynn Appleby is about a week away from an ankle issue, with Nathan Murphy (ankle) and Tyler Brown (shoulder) expected to feature in the next fortnight.

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