YOUNG key position player Lewis Johnston is in contention to make his AFL debut this week as the Sydney Swans tinker with their line-up ahead of their important clash with the Kangaroos in Melbourne.

Following a disappointing home defeat to Hawthorn on Sunday, Swans head coach John Longmire has suggested changes are imminent, with 20-year-old Johnston a possible inclusion.

In his first year at the helm, Longmire is still searching for his best combination as he attempts to guide the club into the finals for the eighth time in the past nine seasons.

Ruckman Mark Seaby, young midfielder Brett Meredith and forward Trent Dennis-Lane are also pushing for selection.

Johnston, who was recruited from North Adelaide as a forward, has impressed in a defensive role in the reserves this season and may have done enough to earn his first senior game.

He was the 12th overall selection in the 2008 draft.

"He's been playing all his football this year down back, apart from last week when he played half-back and half-forward," Longmire told reporters ahead of training at the SCG on Tuesday.

"We put him down back as part of his education process and we're so pleased with the way he's gone about it, he's been fantastic.

"He's really learned another part of his game that he probably didn't know much about before.

"We do have the flexibility of bringing him forward and we're confident he can play as a defender as well as a forward now.

"This time last year we could only say we hope he goes okay as a forward."
The clash with the Kangaroos is an important fixture for the Swans, who are clinging to eighth spot on percentage ahead of in-form Richmond.

Longmire is also considering recalling Seaby, who hasn't played since being a substitute in round one.

Shane Mumford has held down the rucking duties virtually single-handedly, with occasional back-up from the likes of Lewis Roberts-Thomson and Jesse White.

 "We understand there is a big work-load on Mummy and an enormous load to carry every week," Longmire said.

"At some point he needs a hand and not just with a Lewis Roberts-Thomson, but with a Mark Seaby, a genuine ruckman who can shoulder a lot of that load.

"It also relates to our forward line structure as well.

"We know we haven't quite got the structure right, but we're going to trial some things and give some players some opportunities."

Longmire, who played 200 games for the Kangaroos, expects a strong challenge on Saturday following North Melbourne's loss to the previously winless Brisbane Lions last weekend.

"I know North Melbourne reasonably well and when they get criticised, they'll come out the next week and give their best effort," he said.

"So we expect that and we weren't happy with our effort either.

"We need to turn that frustration over our poor effort into a good effort this week."

The views in this story are those of the author and not necessarily those of the Sydney Swans.