Proud North Melbourne coach Brad Scott has praised star Daniel Wells for shouldering the responsibility to "do the job" after declaring himself fit to face Collingwood, despite suffering breathing problems during the warm-up on Friday night.

Wells and fellow veteran Drew Petrie inspired the Roos to a stunning six-goal first- quarter onslaught against the Magpies at Etihad Stadium, setting their side up for a morale-boosting 40-point victory after five-straight defeats.

It came after Wells sent a scare through the camp pre-game when he came from the field during warm-up and underwent a fitness test just 15 minutes before the opening bounce.

But the classy 31-year-old came out firing, racking up 11 touches, winning three centre clearances and dishing off two goal assists to ignite North Melbourne.

"It was very late the decision for him to play, and he just couldn't have responded any better," Scott said post-match.

"We threw him straight in there from the first bounce. We thought (Levi) Greenwood would probably go to him – he knows him pretty well – but Wellsy's response was just sublime.

"He had a bit of an upper back issue, which is not an issue in and of itself, but it was impacting his breathing.

"So until we could free that up we just weren't confident he would be able to work as hard as he needed to work if the breathing issue persisted.

"But our doctors and physios did a lot of work on him and in the end he was confident, so we pulled the trigger."

Scott said Wells, who finished with 29 touches and six clearances, showed his strength of character to set the Kangaroos alight.

"He just made a conscious decision if he was going to declare himself fit, because ultimately the medicos didn't think there was any risk to him, so it was a matter whether he could get through with it," Scott said.

"Once he declared himself fit he was determined to get out there and do the job.

"It just speaks again to the character of Daniel Wells."

After weeks of intense speculation about his future, Petrie bounced back admirably, laying six crunching tackles by the 10-minute mark of the second quarter.

The key forward was in everything early and also booted two majors to finally get some more reward for effort.

Petrie is out of contract, but Scott wouldn't be drawn on what impact his performance would do for his chances of a new deal.

"It's too far into the future. Drew and I have done a lot of work on staying really focused and in the present – and that's really difficult," Scott said.

"We both acknowledge at times we're thinking about 2017 where he's concerned, but we've got to keep it a week-by-week focus for Drew.

"I thought his effort and his pressure tonight was just outstanding. He really led the way in the forward half in terms of pressure."

Scott was thrilled with his side's "combative and aggressive" opening on Friday night, plus the performances of youngsters Ryan Clarke (27 disposals) and Trent Dumont (15, two goals) as the Pies surged from 46 points down to 15 points early in the final term.

"They were terrific, particularly late when it mattered," Scott said.

"Ryan Clarke, I can't think of too many players who have come in and had over 70 possessions in their first three games.

"I think he's one of the brightest young players in the competition … and Dumont again has been really solid and stood up when it mattered."

After losing five-straight games before Friday night's triumph, Scott said the most pleasing aspect was his players blocking out the external noise and staying focused when the Magpies fought back.

Scott was hopeful the Roos could regain sore star Jarrad Waite (hip) for next Saturday night's clash with St Kilda, when Brent Harvey will break the all-time games record in his 427th appearance.

"These are one of the moments in sport when you think, 'Gee, I was glad I was there to witness that," Scott said.