Looking positive: Injured Ben Reid at Collingwood’s training session yesterday.

Looking positive: Injured Ben Reid at Collingwood’s training session yesterday. Photo: Pat Scala

Collingwood appears primed to re-introduce four premiership players into its team for Friday night, making the Western Bulldogs "mission possible" all the more difficult.

Key defender Ben Reid is ahead of schedule on the comeback trail from a quadricep injury suffered in round three, while Dale Thomas and Heath Shaw, who both missed Anzac Day with hamstring complaints, are also in the selection frame for the clash against the Dogs at Etihad Stadium.

After completing three games in the VFL and showing strong form, Pies small forward Alan Didak is also a strong chance to play his first game this season after a pre-season interrupted by an adductor injury.

"We expect all our guys on the short-term injury list to train today - Reid, Shaw and Thomas," Pies director of football Geoff Walsh said today.

"We expect them to all get through, their recovery program says they should all train pretty strong today, so we're hopeful they'll be back this week," he said.

"Those three in particular will have fairly strong claims.

"Ben (Reid) has come up really well, quite a deal quicker than we thought originally."

Didak also trained today and Walsh said the Pies had been impressed with the way the two-time All-Australian had attacked his stint in the VFL, averaging 23 possessions and kicking five goals in three games .

"He pulled up pretty well after last Saturday's VFL match so he's had a couple of games under his belt and performed okay and got a fair bit of the footy," Walsh said.

"So today's session will be critical for him to get through and we expect him to," he said.

"Alan's been quite professional about his whole rehabilitation and when he's been available to play the last few weeks, he's had a real crack."

Walsh also rejected the idea that Nathan Brown's strong comeback in a key defender post last week meant the Pies could afford to be extra cautious with Reid.

Veteran defender Chris Tarrant, who has missed the past three games with a calf injury, trained away from the main group today, but could play in the VFL next week.

"The last seven days he's really got some traction in terms of his rehabilitation program so with a bit of luck, and if it continues to go that way, we think Chris will be able to play in our VFL team next week," Walsh said.

With three players out for the season with long-term knee injuries, the Pies have room on their list to promote a rookie.

Walsh said the club's policy was only to elevate rookies when they are deemed ready for AFL selection, but revealed yesterday that left-foot hard-nut Marley Williams had been discussed in match committee meetings in recent weeks for a possible call-up.