FREMANTLE coach Justin Longmuir has revealed out-of-form All-Australian Michael Walters is in doubt for Sunday's Western Derby with a left hand injury.

The 31-year-old underwent scans earlier in the week after an incident in the second quarter of Sunday's 10-point loss to St Kilda where he had minimal impact with eight disposals and one goal.

"He went for scans," Longmuir told reporters on Thursday. "It's ruled out a bone break at this stage. He's definitely got something going on there."

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Walters trained with strapping on the hand and did not appear overly hindered by the issue when marking or handballing, with Longmuir stating that would form their selection call.

"We just have to see how it functions," Longmuir added.

Walters, who has been used predominantly forward so far this season, only managed seven possessions with no goals in Fremantle's round one victory over Adelaide.

Longmuir admitted Fremantle may need to re-assess Walters' role in the side, if available, given his limited impact in both games this season.

"I definitely agree with the fact that we need to find him some space," he said. "He's still drawing the oppo's best defender and most active defender so we need to look at ways to get him into the game."

Longmuir declared Nathan Wilson (shoulder) available and was "confident" Brennan Cox would be fit to play after spending a week in health and safety protocols.

The Dockers are sweating on the availability of ruckman Sean Darcy (ankle) and forward Matt Taberner (hamstring), while 2020 Rising Star Caleb Serong was a surprise absentee from Thursday training.

Darcy was confined to walking laps at training, while Taberner joined in with the main group and looked comfortable.

"(Darcy) is improving every day. He's going to be touch and go. He'll do minimal today," Longmuir said. "It's a good result considering the action on the weekend. Whether he gets up on the weekend, we feel it's a short-term thing.

"(Taberner) is going to have to get through main training. he's ticked every box so far, but there's some markers he needs to hit at main training today. So far so good, but he's got some pretty important hurdles to tick."

The Dockers were beaten 14-4 in centre clearances against the Saints and Longmuir admitted they may need to re-jig their personnel in the middle with Nat Fyfe (back) and David Mundy (H&S protocols) still out.

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Neil Erasmus, who Fremantle took at pick 10 in last year's NAB AFL Draft, pressed his case for a debut with an impressive display in midfield for Peel last weekend.

"There's always a chance but there's a few things we have to tick off before we get into selection," Longmuir said about an Erasmus debut.

"We're obviously missing a few in the middle of the ground and we were badly beaten there on the weekend so we need to look at a couple of different options."

He added: "I felt we didn’t get the basics of stoppage work right last week and that can be seen around our contest work all over the ground. That's a good start, and we'll look at personnel and structure and see whether there's any way we can support that."