Lachie Hansen was a frustrated spectator throughout North Melbourne's last finals campaign and the important defender is a welcome addition to this year's mix.

The chronic hip problems that sidelined the 27-year-old after round 23 last year lingered into this season as he recovered from surgery on both hips.

Hansen admits he feared the issue could derail his finals ambitions for the second year running but his confidence has grown, along with his influence in the Kangaroos' back half, as the season progressed.

"There were a few times when I did wonder if I was going to get back to even being able to run properly," Hansen said.

"It really took me a while to start to (regain) that confidence and I was pretty sore there for a bit.

"I was probably a bit slow at the start of the year after missing the first five rounds.

"It took me a little while to get used to the pace of the game again but I felt like I slowly started to pick up my form.

"I feel the best I have in a long time and hopefully there's plenty of good things ahead."

Hansen had 21 possessions and took nine marks in the Roos' stirring elimination final win over Richmond in front of just over 90,000 fans at the MCG.

A sudden-death semi-final against the Sydney Swans at ANZ Stadium awaits with the Swans needing to recast their attack without Lance Franklin and Sam Reid.

"We're not sure who's going to come in but whoever does you know they'll play their role - Sydney are a very good side like that," Hansen said.

"Whoever they bring in generally plays very well so we'll have to be on our game to beat them.

"But it's been good to really gel together down back over the last six or seven weeks.

"You know what you're going to get from all of the guys down there."