Fremantle have secured the crucial signature of ruckman Sean Darcy, with the in-form big man confirming a two-year contract extension that takes him through to the end of 2024.

Darcy, who has emerged as one of the AFL's best ruckmen this season, was due to come out of contract at the end of next year, but has agreed to an extension that will take him through to free agency.

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The 23-year-old joins small forward Sam Switkowski and rookie goalkicker Josh Treacy in signing extensions this week, with the pair committing through to the end of 2023.

"I spoke to my parents, spoke to my family, spoke to my friends back home and it was a pretty easy decision," Darcy said on Thursday.

"I'm really enjoying being over here, I've got a really good support system over here, and I call my family whenever I want.

"Hopefully the borders open up pretty soon to the Victorians and I can get Mum and Dad over here, which would be great.

"I feel like the club is going in a really good direction and we have a lot of young people going really well and I'm really close with the majority of them."

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Darcy has enjoyed the best season of his career since being drafted with pick No.37 in the 2016 NAB AFL Draft, ranking No.4 in the AFL for hitouts (30.2) and No.5 for hitouts to advantage (9.8).

He has averaged a career-high 4.1 clearances and pushed forward to be a dangerous target inside 50 at times, ranking 'elite' among ruckmen for score involvements (6.4).

With midfield teammate Adam Cerra yet to sign on beyond this season, Darcy said keeping the Dockers' young core together with the goal of playing finals in the coming seasons was important.

"I think we've got a really young and exciting team that is building at the moment," the ruckman said.

"We're really enjoying each other's company and we're really close as a group, so it's a really good club to be at (and) everyone is coming here wanting to improve every day.

"He (Cerra) is a really close mate of mine, and it's his decision. He's a big boy, he's an adult. I won't get into his ear." 

Darcy will come up against returning Collingwood star Brodie Grundy on Saturday at Marvel Stadium, declaring he had been hoping the dual All-Australian recovered from a neck injury in time for the match. 

"He's one of the best ruckmen in the comp and it's always exciting and nerve-racking going against one of those players," Darcy said.

"You see where you're at as a footballer when you play players like that, so it's exciting to go against him and hopefully he gets up … I'm excited."

Fremantle captain Nat Fyfe remains in some doubt for the clash as he recovers from a dislocated right shoulder, with the Dockers due to fly out of Perth on Thursday afternoon.

Fyfe, who will have final sign off on his availability, stood to the side during light handball drills on Thursday morning, with his ability to regain strength and mobility in his shoulder the key to playing on Saturday.

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