Collingwood coach Mick Malthouse has vowed to take a no risk approach into Saturday night's knockout semi-final clash against St Kilda refusing to declare veteran duo Scott Burns and Simon Prestigiacomo certain starters even though both trained strongly on Wednesday.

And mystery also surrounds the availability of star centre-half-forward Travis Cloke, who failed to train on Wednesday with Malthouse also refusing to guarantee his number one forward would play against the Saints.

All eyes were on Burns as the Pies underwent their main training session of the week at Gosch's Paddock with the Magpies' skipper having missed the past two matches with a calf strain.

And while the 33-year-old completed the session - including match practice - Malthouse said Burns was far from certain to lead the team out against the Saints.

"He is where we thought he would be so we will now weight it up," he said of Burns.

"I don't think the doctor is as convinced (about Burns' fitness) as you or me and he (Burns) has still got a bit of convincing to do."

Burns and Prestigiacomo, who suffered shoulder soreness during the elimination final victory against Adelaide, are likely to be named in the Pies' side on Thursday night but whether they play or not probably won't be known until just before the first bounce on Saturday night.

But one thing is certain if the pair do run out onto the MCG on Saturday night they will have been declared 100 percent fit to play.

"We are not going to take people in there that can't get through games of football," Malthouse warned on Wednesday.

"If something happens on the day, it's out of your control but you do control who plays."

"And in finals football too many sides have been burnt in the past (by playing injured players)."

Malthouse said these days in record interchange rotations, teams could simply not afford to run the risk of players coming into games with an injury query hanging over them then breaking down and not be able to finish the match,

"You've got to be so careful about picking players that can't get through a full game of football and most coaches agree now that anything less than having 22 players available throughout a match compromises your chances of victory."

When asked about Cloke, Malthouse denied his star forward was carrying an injury but significantly refused to say if his key man was a certain starter against the Saints.

"I wouldn't have thought anyone is a definite (starter)," he said.

And Malthouse, a master of the mind games heading into finals, also refused to rule key forward Anthony Rocca making a shock comeback at some stage during September - if the Pies' continue to progress - even though the 31-year-old has not played since round 13 because of an ankle injury.

"He is a player who is still in our (selection) thoughts," Malthouse said of Rocca.