FREMANTLE will consider handing a debut to first-year ruckman Liam Reidy in Saturday's clash against Sydney at Optus Stadium as it waits for further confirmation on the extent of No.1 big man Sean Darcy's ankle injury.

Playing Reidy and maintaining their preferred forward structure is among the options being considered by the Dockers this week, along with moving star recruit Luke Jackson into the No.1 ruck role, as they did in losses against Richmond and Greater Western Sydney earlier this season.

Coach Justin Longmuir said Reidy had put himself "in the discussion" with consistent form over the past month, but the match committee still needed to work through its options.

"Whether we go with another ruck or a key forward or we go smaller, they're the three options," Longmuir said on Wednesday.  

"We've got to make sure the players who come in are in good form and able to contribute in the right way.

"He (Reidy) has been building. He probably started the year a little bit slow, he's had a few hiccups along the way, but he's had some consistency over the last three or weeks.

"Clearly Luke is our second-best ruck on the list, so we've just got to weigh up whether he's best served in the ruck or forward."

Longmuir said the Dockers remained hopeful Darcy would be available before the end of the season after limping from the MCG last Saturday following an innocuous incident against Collingwood.

The club was planning to be without the 25-year-old for at least the next couple of matches, with games against Sydney and then Geelong at GMHBA Stadium in round 20.

When Darcy was sidelined in rounds 13 and 14, the Dockers moved Jackson into the No.1 ruck role and used key forward Josh Treacy as his support in costly losses against the Tigers and Giants.

While Jackson battled some hip soreness following those matches, Longmuir was confident he would be able to deal with the increased ruck load this time if needed.

"It is [a consideration]. Some of the concerns were caused off the back of his spike in ruck loads. He went from second ruck and minimal ruck playing mostly forward to all of ruck," the coach said.

"That was a big jump, which he wasn't used to. This time hopefully he's used to it, because he's already been through it and he's had that taste for being a No.1 ruck and his body is up to it.

"We think he should be right."

The Dockers expect to regain forward Michael Frederick (quad) and defender Hayden Young (ankle) this week, with Longmuir declaring both a "good chance".

Versatile defender Heath Chapman will be eased back from a long-term hamstring injury at WAFL level to build up his fitness gradually.

Asked what the 7-10 Dockers could get out of their last six games, Longmuir said imposing their brand consistently was the goal. 

"When we have focused too heavily on one area of the game, other areas have slipped, so it's consistency across all phases and consistency across the whole game. That's our challenge," the coach said.  

"That comes back to individuals being more consistent across the course of the game.

"That's your individual challenge, but that will feed into what we’re doing as a team.

"We need to use these last six weeks to make sure we're as consistent as we can be. Then what will be will be."