West Coast's quest to keep their top-four prospects alive have been dealt an unexpected blow with Ross Glendinning medallist Matt Rosa out of tomorrow's western derby with a fractured jaw.
Key trio Dean Cox, Daniel Kerr and Luke Shuey were considered those at most risk of missing out through injury, but it was instead Rosa who was ruled out of the Patersons Stadium clash.
The 25-year-old was due to have surgery last night and will miss up to three weeks.
It is a major setback for the Eagles, who named Cox (ankle) and Kerr (hamstring) despite lingering concerns over their fitness.
Shuey missed the start of training on Wednesday but was included in a forward pocket.
Midfielder Tom Swift replaced Rosa and Mitch Brown was also promoted as a like-for-like replacement for suspended Darren Glass.
Fremantle made just one change, adding Zac Dawson to combat West Coast's tall forwards at the expense of first-year player Cameron Sutcliffe.
They resisted the urge to include Zac Clarke, naming Jonathon Griffin as their sole specialist ruckman in a sign his suspect knee should hold up to the daunting test against Cox and Nic Naitanui.
Rosa's projected return means he should avoid missing consecutive finals campaigns.
He missed West Coast's three finals last season after straining a medial ligament in a knee a month out from September.
An Eagles spokesman said he had been injured late in the 98-point thrashing of Brisbane last Sunday, but did not detail the specific incident. He finished the game and trained on Wednesday.
Carlton midfielder Kade Simpson will play his first game in four weeks on Sunday after suffering a similar injury. That makes a round 22 return against Collingwood in Perth the most likely scenario for Rosa.
Coach Ross Lyon this week denied Fremantle would target any particular opposition star, pointing towards Rosa's performance in the round-nine derby as evidence of why that tactic would be folly.
The 124-game Eagle racked up a career-high 43 disposals and kicked a goal as West Coast stretched their derby winning streak to three with a crushing 48-point triumph.
"It's how best that we handle what they are going to dish up, their pressure and their physicality," Lyon said.
"So it's not about the one key threat, because it's about the total system you're coming up against."
Kerr is still far from a certainty after being substituted in last Sunday's win.
Sources close to the midfielder said he had suffered a small tear to go with minor muscle bleeding.
Midfielder Bradd Dalziell was named as an emergency and would be the likely replacement for Kerr.
Dawson will play his first game since round 11 despite a modest performance for WAFL club Perth last Saturday.