Collingwood forward Chris Dawes has gone from limping to soaring in 24 hours, seemingly eliminating a huge AFL preliminary final selection headache for the Magpies.

But while Dawes trained strongly in front of hundreds of fans on Wednesday to indicate a knee injury won't stop him facing Sydney at ANZ Stadium on Friday night, a calf injury kept Alan Didak inside.

After coach Nathan Buckley had said on Tuesday that Wednesday's training session was the opportunity for Dawes and Didak to prove their fitness, Didak's no-show casts serious doubt on his selection prospects.

But the Magpies said the half-forward trained alone indoors and remained in contention.

"We're going to give him every opportunity to prove his fitness and to this point he's done everything the physios and doctors asked him to do," Collingwood director of football Geoff Walsh said.

Dawes looked a very unlikely starter at the Magpies' Tuesday recovery session, when he did not run or kick and limped while walking.

By Wednesday, he was running freely and kicking goals from beyond 50m.

By late in the session, Dawes had built enough confidence to leap for marks using a marking bag.

He then had a one-on-one session with coach Nathan Buckley, showing he could also move laterally by gathering ground balls rolled to each side of him by the coach.

Before training, Magpies football and coaching strategist Rodney Eade said Dawes' knee medial ligament strain was minor and while bone bruising had caused some pain, that was reducing.

"There's a little bit of a strain there, but with the impact too he had a bit of bone bruising," Eade said.

"So there's a bit of pain there, I think that probably causes the limp.

"We think that will subside relatively quickly."

Eade said given Dawes' importance as a back-up ruckman, if he was even 90 per cent fit, he would most likely play.

He said Didak was still experiencing calf soreness, after receiving a knock on Saturday night.

"He's still got a little bit of discomfort, so it just depends how he runs and how he moves," Eade said.

"Then we've got to take into account obviously fatigue, the six-day break."

Small forward Ben Sinclair, dropped for Saturday night's semi-final win over West Coast, shapes as Didak's potential replacement.

But Eade suggested Collingwood could name Didak and Dawes on Thursday night and leave the final call until Friday afternoon.