COLLINGWOOD star Dayne Beams is only a 50-50 chance to face Carlton at the MCG on Saturday while big man Mason Cox has already been ruled out.

A sore hip prevented Beams from joining the Magpies' main session on Thursday as Cox watched on with tape around the right ankle he injured against Essendon on Anzac Day.

The second-placed Pies, who will already be without Taylor Adams (adductor) for the next month, are prepared to give fellow inside midfielder Beams until game day to prove his fitness for the clash with the second-bottom Blues.

In better news for the Woods, role-playing midfielder Chris Mayne could make a rapid return after missing just three games with a back fracture, while defender James Aish is also back in contention after overcoming the concussion that has sidelined him for the past two games.

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"Beamsy pulled up a little bit sore in the hip so he wasn't able to do the session today, which would count against him in some shape or form, but (there is) still a couple of days for us to go yet," Collingwood coach Nathan Buckley told reporters after training.

"He's 50-50 at the moment, but he's an elite player for us so we'll give him right up until the death."

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Cox was in a moonboot at the same stage last week and has made progress but the Magpies want the giant forward/ruckman to completely get over the problem before bringing him back.

"He's actually moving around OK and has come on pretty well this week but he's a big boy and there's a lot of load going through that lower leg so we want to make sure he gets that right," Buckley said.

When Cox does return, the Magpies might well face a selection dilemma that is likely to place pressure on recently returned Ben Reid and possibly even Brody Mihocek, but Buckley dismissed any suggestion that the key forward duo are vying for the same spot.

"No. They've got the opportunity to perform their roles and maintain their current form. Any speculation beyond that is … It changes pretty quickly with injury or form, match-ups against the opposition, so it's too simplistic to think that two blokes are playing for one role," he said.

Buckley said Mayne, who suffered his back injury in the round four win over the Western Bulldogs, had trained strongly over the past fortnight.

"I think his hand's up – it's just a matter of whether he fits our balance," Buckley said.

Aish moved well at on the track but Buckley said a final call was yet to be made on whether he would return at AFL level.

If Beams fails to come up and the Pies have to replace two key ball winners, they would likely turn to big-bodied onballer Rupert Wills, who has been in good form in the VFL.

"He's probably the best-performed of our mids in the VFL and has been around the mark for a couple of weeks now, so that would probably be the first port of call," Buckley said.

"Getting that balance right between insiders and outsiders is crucial as well so that's in our consideration."