North Melbourne has a warning for Geelong utility Mark Blicavs – try to run ruckman Todd Goldstein off his feet at your own peril.

The Cats will enter Friday night's semi-final without a genuine ruckman after Hamish McIntosh – their last standing big man – was ruled out with knee soreness.

The former Kangaroo joins other Geelong rucks Dawson Simpson (back) and Nathan Vardy (knee) as unavailable to go up against Goldstein and Ben Brown, leaving the 198cm Blicavs to carry the load.

While Blicavs' main weapon is his endurance, stemming from his background in steeplechase, Kangaroos' assistant coach Leigh Tudor has warned Goldstein won't be beaten if the Cats' plan is to run him off the park.

"Teams in the past have tried to run him around and he's always put up with that, he's got a big motor so he should be fine," Tudor told AFL.com.au.

"It's just something different for him. He's used to playing against the big blokes and now with whoever they bring up, it's going to be a different challenge.

“’Goldy’ has proven over a number of years he can ruck all day, so we don't expect that to change.

"There's a few things we can do to help him out as well."

Geelong coach Chris Scott has suggested Josh Walker and Tom Hawkins as potential back-ups for Blicavs, which means there could be some shuffling within the Cats' forward line.

Tudor said Goldstein would be ready for whatever was thrown at him despite the challenge of not really knowing which way the Cats would line up.  

"It's unpredictable but every week there's generally a main ruckman and a forward that comes in to help out for a little bit," he said.

"Goldy is used to that, he's had a lot of different scenarios over the last few years so he's more than ready for the challenge.

"They've got some runners and some good marking players, a few players they can throw in there, but for Todd he's just got to worry about what he can do best."

Friday night will be the first time the Kangaroos have been able to play Brent Harvey, Nick Dal Santo and Daniel Wells in the same team against Geelong.

After being cut up by the Cats on the outside when they lost to them by 32 points in round 19, Tudor said the trio would make a difference this time around.

He also said the Roos had learnt from that clash and believed they would respond as a midfield group, as they did against Essendon last Saturday night.

"Essendon did the same thing to us in round one and we seemed to fix that up last week," he said.

"We're a different side to what we were the last time we played them so hopefully they don't get as much easy ball as last time.

"It's really exciting, [Harvey, Dal Santo and Wells] can all play in a number of spots and they're just really hard match ups.

"They're experienced players that play well in big games and we can't wait for Friday."