Fremantle forward Lachie Schultz has been ruled out for Sunday's clash with Essendon at Marvel Stadium as he enters the AFL's Heath and Safety Protocols.

The news is a blow for Fremantle with the 24-year-old kicking six goals from four games so far this season and winning the Glendinning-Allan Medal in the round three RAC Derby.

Senior Coach Justin Longmuir confirmed the news in Thursday morning's media conference, saying versatile forward Bailey Banfield was the likely replacement.

He added that Schultz is the only player expected to miss under the Health and Safety Protocols.

Key defender Alex Pearce remains a chance to return as he looks to recover from a sore ankle while midfielder Caleb Serong only has to get through Thursday's main training to lock in his return from a minor knee injury.

"I know Alex has some pain in the front of his ankle joint," Longmuir said.

"These things can get to 85 or 90 per cent right really quickly.

"It’s that last 10 per cent that can take a bit of time. We think it’s improved, but we want to make sure he’s 100 per cent.

"We’re really confident he will get up for this weekend, and if that’s not the case, then he is a certain starter next week."

Longmuir added Fremantle were hopeful of having captain Nat Fyfe back before the bye.

"We hope to see Nat back a couple of weeks before the mid-season bye," Longmuir said.

"It’s hard to put an exact timeframe on his injury, but he’s progressing really well."