FREMANTLE could be sweating on Joel Hamling's cognitive test ahead of a tough showdown against Greater Western Sydney, with the key defender joining Nat Fyfe in needing to overcome concussion ahead of next Saturday's clash.

Hamling suffered blurred vision after a second-quarter incident during the Dockers' gutsy 13-point Western Derby loss to reigning premier West Coast on Saturday night.

With the Giants' three-pronged tall forward line Jeremy Cameron, Jeremy Finlayson and Harry Himmelberg combining for eight goals in a landmark win in Geelong earlier on Saturday, Hamling's availability will be crucial for the trip to Canberra.

If he fails to recover, Brennan Cox could be in line for a recall as a defender after playing at centre half-back for Peel.

DOCKERS FALL SHORT Full match coverage and stats

"It was a concussion (for Hamling). I didn't really see the incident, I think he hit his head on the turf and got some blurred vision, so a bit different, but he'll go through the same protocols that everyone does," coach Ross Lyon said. 

Fyfe was ruled out of the Derby after a heavy hit six days ago against St Kilda left him battling headaches.

The midfield beast was sorely missed around clearances in the eighth-straight loss to the Eagles, who dominated stoppages 39-26.

"Hopefully at some point he'll be symptom-free, he probably is now, then he'll sit the cog state (test) and if he clears it he'll play," Lyon said.

"It's a binary yes or no answer on that.

"It would be dangerous for me to speculate. It would certainly be uncharted waters for myself."

In Fyfe's absence, veteran David Mundy (36 disposals, 10 clearances) was outstanding as the Dockers pushed red-hot favourite West Coast all the way.

But errors by foot continued to haunt Fremantle, which had two more scoring shots against the Eagles but scored a wasteful 7.14 – after going into half-time with 1.9 on the board.

Key forward Matt Taberner was the main culprit, booting 2.3, with two shots failing to score.

WATCH Ross Lyon's full post-match press conference

"A little bit of damage was done (early), they scored a few goals out from centre-back, which hasn't really happened to us," Lyon said.

"But once we tidied that up, I thought we competed, not perfect, but quite well and got more composed with the ball.

"We just rushed a bit early, a bit excited really.

"I think once we played with more composure and the second half we fixed up our composure on entry as well we certainly challenged them more.

"They just made us pay early.

"We're all a bit frustrated. They're the reigning premier, very efficient, very strong team, so I was pleased with the way we never gave up.

"But that's been reflective of all our performances. Our effort and team dynamic is incredibly strong at the moment."

The Dockers drop to 2-2 after the defeat, and face a challenging month with the Bulldogs (home), Adelaide (away), Richmond (home) and Essendon (away) to come after next week's Giants clash in Canberra.

Find In the Game on Apple Podcasts, Google Podcasts or Spotify