Collingwood coach Mick Malthouse admits he's taking a punt by going in with just one specialist ruckman against Fremantle giant Aaron Sandilands at the MCG on Saturday.

Malthouse conceded that Sandilands was virtually guaranteed to get first hands on the ball regardless of who he was up against, and believed the Magpies' resources could be best used elsewhere.

For that reason Josh Fraser's back-up, Cameron Wood, was one of three players axed from the line-up which ran over the Sydney last weekend to chalk up a four match winning streak.

Midfielder Scott Pendlebury (knee) was a forced omission.

"He's supposed to be 123 kilograms and someone told me that's well and truly under," Malthouse said of Sandilands.

"He's almost immovable, he's got 211 centimetres of height, he's got a reach like a sick dog, so how do you get near him?

"It's a battle for two ruckmen and we've just elected to go with Josh and we'll see whether we can cater for the other ... with (Chris) Dawes, (Travis) Cloke and (Leigh) Brown of equal size who will probably need to go through the ruck.

"Is it punt material? I guess sometimes you do, I don't know whether it's a total punt.

"We think we can get better value out of Josh probably playing more time in the ruck then he does sitting on and off the bench."

Malthouse said Wood was "slow to mature", comparing him to Sydney's star ruckman Darren Jolly.

"We haven't forgotten that Cameron Wood is only a young man who needs time and when he gets to the power stage," he said.

"When he puts some kilos on, he will be a very good ruckman for us.

"He's a smart player, a one-touch player, can kick goals, knows where to position himself, it's just a matter of time."

Young key position player Dawes has been included for the first time this season, with Malthouse rating him as vastly improved on last season.

"Dawes played in our last six games last year and he's much further advanced than last year," Malthouse said.

"He's a lot stronger and much more aware of what the requirements are."

The coach said the other changes, with key defender Nathan Brown back from a knee injury and youngsters Tyson Goldsack and Dayne Beam included while Irishman Martin Clarke and first-year midfielder Steele Sidebottom dropped were about keeping the pressure on his side.

"We've got to keep pressure on players and pick the best side that's appropriate for the opposition," Malthouse said.

"We always look at our side and think that if the side has won or lost it's still looked at in the same position as trying to pick the best side for the next week.

"And under those circumstances a couple of those players have made way because of the form of the other players who are coming in."

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