The alarm bells were ringing again.

Jared Polec's 2015 season – while he was still at Port Adelaide – ended after only five games, because of the discovery of a stress fracture in the navicular bone in his left foot.

The "unusual" shape of Polec's bone meant surgery wasn't an option if he wanted his AFL career to continue, and it took consulting a series of specialists before one (Dr Kim Slater) recommended the natural healing path.

History shows he returned the next season to play 17 games, then he missed just one match in the past three years, including all 22 for new club North Melbourne in 2019.

Then, in the last week before the Christmas break last year, Polec felt a pain he hadn't since his career-threatening navicular setback.

The 27-year-old immediately stopped training, and soon after underwent MRI and CAT scans to find out what was wrong.

"I'm always going to have pain in my foot but it was a new sort of pain, under the one I've had for a few years, so that was the alarm bell," he told AFL.com.au this week.

"We caught it pretty early and didn't push it. As soon as I felt it, I stopped, which was a big thing as well and helped us in the long term.

"There was no crack, no fracture (but) we had the radiation scan and it lights up when there's a bit of stress through the bone and it lit up in that spot."

Polec stuck to upper-body exercises and stayed off his legs as much as possible for the next three weeks but the next step didn't prove straightforward.

He and the Kangaroos' medical staff initially disagreed on the treatment plan but compromised on fortnightly meetings, rather than a long-term program, to constantly reassess how his injured foot was progressing.

Repairing any sort of navicular bone issue requires certain loading to promote healing – otherwise it can weaken – and this is partly where they had differing views but it didn't take long for some "give and take".

Polec was keen to do more, whereas the medicos wanted to play it cautiously with the club's long-term investment, who arrived on a lucrative five-year deal in the 2018 Telstra AFL Trade Period.

"I sat with the staff and we weren't seeing eye to eye at the start but we eventually came together, worked out a plan and ticked the boxes to get me right for round one," he said.

"If I did (suffer) a stress fracture at the start of the season, it wouldn't be good for the club, it wouldn't be good for the docs and physios or myself, so it's good we found a line and we were all willing to work together.

"The experience helped on my side, and the caution helped on their side, too, because I could have definitely pushed a bit harder at stages I shouldn't have pushed."

Polec returned in North's second Marsh Community Series game against Sydney, winning 17 disposals and kicking a goal in 60 per cent game time.

He pulled up well and made it to the start line for the premiership-season opener, where he accumulated an equal game-high 25 touches and 526m gained.

Polec's sole complaint was his kicking efficiency – including hitting the post from a close-range set shot in the opening quarter – with the Roos rallying from a 31-point second-half deficit to triumph.

North Melbourne had lost nine of its previous 10 round one games, so a winning start to a season was a long time coming.

For Polec, it was the continuation of his strong finish to last season.

Kangaroos coach Rhyce Shaw even highlighted him as being "invested" in a club video released post-match for his act of lending teammate Ben Jacobs a pair of boots during a pre-season session.

It's all part of a mental rewiring that occurred during last year's bye week, when Polec was able to recapture what worked for him in his career-best 2018 season.

"Probably last year, going to a new club, I felt a bit uncomfortable and was trying to live up to an expectation of doing really well every game," Polec said.

"But just lowering that and getting back to the way I know I can play footy (was important), and that's the way I finished off the year. 

"It was a good stepping stone into this year and I'm just trying to be a bit more open about myself and the position I'm in and trying to invest with the younger players."