Liam Shiels and Tom Powell will need to prove their fitness before North Melbourne heads down the highway to face the Cats on Sunday.

Shiels has only missed one match since debuting for the club in Round 1, with a concussion ruling him out of the Round 11 match-up with Collingwood.

However, the midfielder is currently dealing with a calf complaint that could see him sidelined this weekend.

"Liam had an incident where he felt his calf/Achilles tighten up in the fourth quarter (against Adelaide) in what was an unusual presentation of symptoms," head of performance Kevin White told NMFC Media.

"Scans on Sunday showed injury to his plantaris tendon, which is connected to his calf at the level of his ankle.

"He's made significant improvement over the past 48 hours but is still in some doubt for this week. He'll look to prove his fitness at the back end of the week to be available for Sunday’s game."

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Since returning from an ankle injury he sustained against Melbourne in Round 7, Powell has experienced "more stiffness" in the same area over the past number of weeks.

"This (stiffness) has had a compensatory effect on his knee/iliotibial band where he has been loading more through this region due to a stiffened ankle with running mechanics," White detailed.

"Tom will need to show improved ankle function and have the ability to run and function without inhibition in proving his fitness this week."

Hardened defender Jack Ziebell is available for selection despite having his knee landed on by the opposition in Round 16, while Aiden Bonar has been given the green light to return after recovering from his own knee injury.

"Jack had his knee driven into the turf causing acute soreness so we went conservative with him late in the final term. He will fully train on Thursday and be available this week," White said.

"Aiden has made great progress with his strength and on-field loading over the past two weeks and has integrated back in with the main group as of this week."

After dislocating his shoulder in the VFL earlier this year, rookie-drafted ruck Hamish Free is set to go under the knife, ruling him out of the rest of the campaign.

"His follow-up assessment with imaging and the specialist has shown insufficient healing of that shoulder injury that would enable high long-term function," White said.

"He will undergo shoulder surgery in the coming week officially ending his playing prospects for the remainder of the 2023 season."

Key forward Charlie Comben is expected to return in approximately five weeks and will look to run on the AlterG treadmill at the end of this week or early next week.