Brownlow medal favourite Nat Fyfe is sore - and that spells bad news for North Melbourne's defenders.
Fyfe trained away from the main Dockers' group on Friday before the session went behind closed doors, raising questions about his fitness.
The 23-year-old hasn't been the same since copping a nasty cork to his right thigh on July 12 from Hawthorn star Sam Mitchell.
The soreness from that knock resulted in a slight change to Fyfe's running style which, in turn, resulted in a minor groin injury.
Making a successful return in last week's western derby, Fyfe is expected to take his place against the Kangaroos at Etihad Stadium on Sunday - but not necessarily in the midfield.
With Fyfe still shaking off some niggles and spearhead Matthew Pavlich (achilles) ruled out, coach Ross Lyon will consider using Fyfe as a key forward against North Melbourne.
Fyfe is one of the best-contested marks in the competition, and his presence up forward would give Fremantle a dangerous target to kick to.
"To get something, you've got to give up something," Lyon said of the prospect of taking Fyfe out of the midfield.
"Gavin Brown was one of the greatest wingers of all time. When Collingwood needed a centre half-forward, he went and played centre half-forward for a few years.
"That's what great players do. They move around, they contribute to their team and they go where the team needs them.
"So if the team needs Nathan to go forward, he'll go forward."
Defender Chris Mayne could also be thrust forward to join fellow backman Alex Pearce in a makeshift attack.
Lyon joked that 177cm goalsneak Michael Walters had become the club's best power forward in the wake of injuries to other players and poor form.
Pavlich has a history of achilles tendon issues, missing 12 weeks in 2013 after undergoing surgery.
But Lyon isn't overly concerned about the current complaint.
"I think it will be mischievous to suggest it's anything like the past," Lyon said.
"It's a bit of a flare-up and he should be ok. It is not a big issue."
Fremantle still need to win two of their remaining three games to secure the minor premiership, while the Kangaroos are eyeing off a top-four berth following six straight wins.
The Dockers have been boosted by the return of defenders Luke McPharlin and Zac Dawson, while North Melbourne have brought in Ryan Bastinac and Jamie Macmillan to replace Jack Ziebell (suspended) and Taylor Garner (dropped).
Fremantle midfielder Nick Suban was forced to take a course of antibiotics during the week after being bitten on the arm by Eagle Chris Masten.
Suban was criticised on Twitter for giving evidence against Masten at the AFL Tribunal, but Lyon could see the funny side.
"I thought Twitter was dead. A few of them need to get on a new platform - Instagram is the new platform boys," Lyon joked.