With former captain Brent Harvey coming out of contract at the end of the year, Drew Petrie expects nothing less than a one year extension to be offered and signed given the veteran's solid form so far this season.

"His efforts so far this year have been great for us. I suppose no longer do we expect him or need him to be our best player each week as long as he contributes and on the weekend, or on Friday night he had 20 possessions and kicked one goal, so if he does that every week, that's all we can ask," he said on Channel Seven's Game Day program on Sunday.

Asked about North's remarkable scoreline against Carlton of 24 goals and just 5 behinds, the vice-captain said it's hard work on the training track finally paying off.

"It is practice, it's just mental strength, mental toughness when you have those hard shots during games. Carlton had only three or four less scoring shots than us but we managed to win by about ten goals."

That mental toughness has only been developed in the second half of the year and came about when the Roos hit rock bottom.

"It's probably been the mental resilience within our group that wasn't quite there at the start of the season, but after we got belted up by Hawthorn before the bye, that was a bit of a turning point where we realised we need to be able to concentrate and become a bit tougher mentally throughout the whole course of the game."

The side's remarkable turnaround has also been attributed to some significant form revivals from players who usually fly beneath the radar.

Petrie also commented on playing alongside some other tall timber in Robbie Tarrant and Lachlan Hansen in the forward line.

"They've been great in the last five games we've played together and last week against West Coast, Robbie Tarrant kicked four and this week Taz just had the one and Lachie and myself go amongst it, so hopefully we can stretch a few more defenses in the coming weeks as well."