Sean Darcy warms up before the round 22 match between Fremantle and Geelong at Optus Stadium on August 10, 2024. Picture: AFL Photos

FREMANTLE ruckman Sean Darcy remains in doubt for Sunday's must-win clash against Port Adelaide as the Dockers prepare to make an early call on the big man's availability. 

The Dockers gave Darcy until the last moment to prove his fitness against Geelong a fortnight ago as he battled a knee issue that has now sidelined him for two matches. 

But coach Justin Longmuir said it was more likely a decision this week would be made after assessing Darcy at training on Thursday, with the big man joining the main group for periods but still appearing restricted. 

The 26-year-old trained separately with injured captain Alex Pearce to start the session, doing run-throughs, short kicking and some groundball work before lining up in match simulation for the second team as Liam Reidy rucked for the likely AFL line-up. 

Speaking before the session, Longmuir said he was not able to declare Darcy would return until watching him complete the session. 

"He's improved, but he's not across the line yet," Longmuir said on Thursday. 

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"He's got to get through training and he's got to do a fair portion to be able to prove himself. 

"We won't take him in if he's not right. We'll get a good understanding of what he can get through and what his pain levels are like, and we'll go from there."

Darcy was replaced late by veteran forward Matt Taberner against Geelong before Reidy was brought in to lead the ruck against Greater Western Sydney in a two-ruck structure that worked better for the team. 

Longmuir said a more certain build-up to the Port Adelaide clash on Sunday would be preferred, rather than leaving a decision late.

"We were happy with the way Reidy went last week, and for the stability of the team, that (an early decision) is probably the best thing. And for Sean and the individuals involved," he said. 

The Dockers will face other distractions on Sunday as they await the results of matches involving Carlton and the Western Bulldogs, knowing they will need one of those teams to lose if Hawthorn beats North Melbourne on Saturday. 

Longmuir said he spoke to the players about sticking to their normal pre-game routine, even if that involved watching other games in the build-up to Fremantle's match. 

He said the scenario facing Fremantle would be discussed pre-game to make sure the players had clarity and were not running out at Optus Stadium with doubts in their mind. 

"I think our process has allowed us to be in most games this year and allowed us to put a pretty consistent level of footy out there," he said. 

Justin Longmuir looks on during the R23 match between Fremantle and GWS at Engie Stadium on August 17, 2024. Picture: AFL Photos

"Whether we're alive in the season or not, we still want to put our best foot forward. That's been the message to the players. 

"Prepare as normal, put all our efforts into Port, and we've got to get the win no matter what. 

"Our players are intrinsically motivated anyway. They just want to go out there and, whether finals are on the line or not." 

If the Dockers are able to qualify for finals, Longmuir said he was really confident key forward Josh Treacy would be fit to play after battling a knee injury and hopeful key defender Pearce (arm) would also be available.