The western derby war of words has well and truly begun, with Fremantle coach Mark Harvey claiming a leak of sensitive team information helped arch rivals West Coast achieve victory when the clubs last met in round eight.

Ahead of Sunday's high-stakes re-match, Harvey unleashed a remarkable derby bombshell by alleging West Coast became privy to crucial details of Fremantle's team set-up prior to the Eagles' 33-point win in May.

In the lead-up to that clash, word got out that goalsneak Hayden Ballantyne would miss due to a hamstring injury.

Ballantyne was named in the side but was withdrawn prior to the bounce, while the Eagles left out Daniel Kerr and Andrew Embley at late notice.

It's unclear whether Harvey's comments were directed over the leak of knowledge over Ballantyne or something more sinister, but either way the outburst is sure to add extra spice to the most important derby since 2006.

"A lot of things happened throughout the course of the week and then in the lead-up to that game, wasn't there, if you remember," Harvey said on Thursday.

"I think some of our intelligence got out ... just in (terms of) some of the structure. Personnel structure I'm talking about.

"A lot of sports overseas, they have lock-out training sessions all year around.

"I spoke to (English Premier League club) Liverpool officials in the last couple of days and they've got their own training venue where no one's let in.

"But what verbally you say, you can't shut that up sometimes.

"So you can train for it and hide it (sensitive team information), but not necessarily (control) verbal conversations."

Harvey declared he had a "fair idea" where the breach occurred, but refused to elaborate.

"I'm not speculating, I'm just telling you how we saw it," he said.

In somewhat awkward circumstances, Harvey aired his thoughts while seated next to Eagles coach John Worsfold.

"I'm not sure where all that's come from," a surprised Worsfold said.

Irrespective of where the leak occurred and indeed how serious it was, Harvey was confident the issue had been addressed and his team would be all the better for it.

"We'll see in time (whether we put in a better performance). But I'd like to think our team is in a better position than it was last time," Harvey said.

Not since 2006, when West Coast won the premiership and Fremantle made their first ever preliminary final, has so much been riding on a western derby.

The fifth-placed Eagles sit just two points adrift of the top four, while the sixth-placed Dockers are just a game further behind but far from assured of a top-eight finish.

Despite the high stakes and potential rewards on offer, both teams resisted the urge to rush back injured stars, with West Coast giving Kerr another week to recover from a series of sore spots and Fremantle ruckman Aaron Sandilands handed more time to recover from his toe complaint.

The Eagles left out Koby Stevens but included Ashton Hams, Mitch Brown, Pat McGinnity and Brad Sheppard on their extended bench.

Dockers defender Nick Suban is the frontrunner to replace Roger Hayden (broken leg), but Ryan Crowley, Peter Faulks and Jayden Pitt are also chances to play after making the 25-man squad.

Brought to you by AAP © 2024 AAP