North Melbourne is confident Robbie Tarrant and Drew Petrie will be fit to play in Saturday night's preliminary final against West Coast.

Tarrant appeared North's biggest injury concern heading into the Eagles clash after he withdrew from last Saturday night's semi-final against the Sydney Swans with a minor groin strain suffered early in North's pre-game warm-up.

Petrie suffered a knock to his right knee in a marking contest late in the first term of North's victory over the Swans and, after leaving the ground for treatment, copped a few more knocks to it when he returned.

Coach Brad Scott told reporters on Wednesday he expected both Tarrant and Petrie to play against West Coast, while the Roos coach also refused to rule out the possibility star midfielder Daniel Wells would return for his first senior game since round two.

"I think Robbie will be OK. He was really close to playing … but the philosophy of playing 100 per cent fit players is a good one in finals," Scott said.

"We had Luke McDonald there ready to go, so we took no risks which means we probably think Robbie will be right, but he'll still have to have a fitness test later in the week.

"We think (Petrie) will be OK and the fact that he came back out on the ground and performed really well suggests that he'll be fine.

"He was a little bit sore straight after the game, but Drew's even making jokes about it, so that suggests he's pretty confident."

Tarrant moved well in a series of run-throughs he completed with Petrie ahead of North's main training session on Wednesday.

Running at around three-quarter pace, Tarrant did not seem at all inconvenienced by his groin and finished each 80m repetition well ahead of Petrie.

The key defender then completed a set of agility drills before changing from his runners into football boots and joining North's main group.

Tarrant shapes as a vital inclusion for the Roos as they prepare to take on an Eagles forward line boasting talls Josh Kennedy, Jack Darling and resting ruckmen Nic Naitanui and Callum Sinclair, while Petrie and fellow talls Jarrad Waite and Ben Brown could give the Roos a vital edge by stretching West Coast's undermanned defence.

Wells has not played a senior game since he was substituted out of North's round two win over the Brisbane Lions with an Achilles tendon injury.

The 30-year-old returned in the VFL early last month and played three consecutive games before suffering a minor calf strain.

Scott said North was confident Wells had done enough fitness work if called upon against the Eagles, but conceded he faced a challenge to break into the Roos' 22 after their impressive finals wins against Richmond and the Swans.

"He'll train today and put his case forward. He's feeling more confident than he has at any point this season of getting back out and playing, so we'll give him every chance," the Roos' coach said of Wells.

"We'd love to have him in our side, but he's got to be very close to his best to force his way in.

"We're pretty confident in the level of work that he's done, albeit not at match intensity. He just hasn't had enough matches to do that, but that's only been through circumstance.

"We're pretty confident that our sports science guys can get him in good nick and then it becomes a match committee decision as to whether we play him."

Scott also confirmed that the last-minute move to replace Robbie Nahas with Kayne Turner in North's selected team against the Swans had been a purely selection-based call.

Scott said it had been a line-ball decision to omit Nahas, with the former Tiger in the selection mix for Saturday night's game.