NORTH Melbourne veteran Drew Petrie is confident Robbie Tarrant will be fit to take his spot in the Kangaroos' preliminary final clash against West Coast, despite the key defender undergoing scans on Sunday.

Tarrant was a late withdrawal from the Roos' semi-final upset of the Sydney Swans after he tweaked an adductor muscle while kicking in the warm-up.

But Petrie, who also had a precautionary scan on his swollen right knee after arriving back in Melbourne, told AFL.com.au that Tarrant was likely to be available for a vital job on one of the Eagles' star key forwards Josh Kennedy or Jack Darling.

"Yeah, I do (think he will be fit). It was a good thing that it happened in the warm-up, so that the movement wasn't at game speed, therefore it didn’t have the opportunity to damage it too badly," Petrie said on Sunday afternoon.

"He kicked once and I think it grabbed, then he kicked again and it was still sore. So he went off immediately and got assessed, and I don't think the physio felt they had enough time to clear him to play.

"It's a bit tight, his groin, and by him not playing it's given him another day's rest."

Meanwhile, Petrie underwent a precautionary scan on the knee he injured early in North's 26-point win over the Swans.

Late in the first term the power forward took a big pack mark at half-forward, winced in pain on landing and took some time regain his feet.

Petrie left the field for treatment but played out the match and received more knocks to the trouble spot that caused him further discomfort. 

He was one of the most dominant big men afield with 14 possessions, nine marks and 1.3, despite what he believes is just a 'corky' to his knee.

"I just had a couple of knocks in the same spot and they happened about five minutes apart, so I was sore when it happened the second time," Petrie said.

"I went off the ground about five minutes later and the physios and doctors did all the tests and structurally everything that they prodded for was fine, so I was no dramas to continue playing the rest of the game.

"There was some swelling there, so they expect there might be some bruising in the area. It is a precautionary scan, given the time of year. If it was one of those things that happened in season you might not bother about it.

"But you need 22 fit blokes going into a preliminary final, so we just want to make sure everything's fine."

Petrie was also sporting five staples in his head on Sunday after a heavy collision with Gary Rohan, which saw the Swans speedster hospitalised and with his left eye swollen shut.

"Gary Rohan's obviously in a fair bit more pain than what I am. He showed more courage in the incident running back with the flight, whereas I was running into the footy," Petrie said.

"I knew the contact was coming and you could sense that he did as well, we just both had to go for it.

"I was a bit sore in my knee again when that hit the deck, so I was a bit more worried about that than my head."

Petrie said the Roos wouldn't look back at their 96-point elimination final thumping from the Eagles at Domain Stadium in 2012 for motivation this week.

And he was quick to deflect the suggestion that North's tall forwards' marking power might give the Roos an edge over the Eagles' undersized backline.

"Much has been made of who's missing in West Coast's side all year, but they've managed to make it to where they are now," Petrie said.

"They've been able to combat any tall sides. I think it's the West Coast tall forward line that's going to the worry this week."