North Melbourne's Mason Wood to miss six to eight weeks after undergoing knee surgery

It is the latest in a series of injuries to strike at Arden Street, where early-season success has turned into a tumble down the ladder.

Wood hurt himself in the Kangaroos' loss to West Coast on the weekend and coach Brad Scott said he had been under the knife to repair a medial ligament.

Scott conceded the forward would struggle to be ready for the finals series.

"It's going to be a tight run back, but our attitude and speaking to Mason is to do everything we can to try to get him back," he said.

In better news for North, Nick Dal Santo has recovered from a minor illness that had forced him out of the Roos' loss to West Coast.

"He's trained the last couple of days and looks pretty good, so he should be fine," Scott said.

Utility Jarrad Waite has been missing with a sore hip and and star midfielder Daniel Wells has been nursing a calf injury – losses that had proved difficult to cope with, Scott conceded.

But he said it had also been an opportunity to look more closely at new recruit Ryan Clarke and at Wood.

"I think the upside of the second half of the year is that we've exposed some young guys, played a lot of players and we'll get a lot of our senior guys back," he said.

Drew Petrie has been the subject of criticism for his recent poor form, kicking just seven goals in the past seven games.

But Scott defended the veteran forward, saying those outside the club did not understand the value of Petrie's defensive efforts.

The coach said he had not "for one second" considered dropping Petrie to the VFL.

Should North Melbourne beat Port Adelaide this weekend, they will be close to cementing their place in the final eight.

Scott said the players were focusing on getting back to playing their best football, after falling from first position on the ladder to eighth with consecutive losses to Geelong, Hawthorn, Adelaide and the Eagles.

"We've been thereabouts with a lot of things we've been trying to do, but they haven't been polished performances and they haven't been good enough to get us a win," he said.

Despite their slump in form, Scott said his players were in good spirits.

"I didn't really need to bring the players back down to earth when we were winning a lot of games in a row, and I haven't had to pick them up this week either, they've driven that really well themselves," he said.

"That's been really pleasing from a coaching perspective, they're really focussed and eager to get out and work hard and get better as a team."