FREMANTLE could be without important wingman James Aish for multiple matches because of concussion as he recovers from a heavy collision with Richmond forward Rhyan Mansell. 

The Dockers face a crunch road game against Greater Western Sydney on Saturday and will be without Aish and ruckman Sean Darcy (hamstring), while star midfielder Caleb Serong is managing an ongoing ankle niggle.  

Aish is a significant loss after an impressive season as the Dockers' mainstay wingman, but coach Justin Longmuir said the club would be cautious with the 27-year-old given his history of head knocks. 

The former Collingwood and Brisbane midfielder returned to training on Wednesday and jogged laps after the heavy collision with Mansell, which earned the Tiger a three-match suspension.  

"This isn't Aishy's first concussion, so we'll take extra precaution and make sure we get everything right," Longmuir said on Wednesday. 

"I'm a senior coach and hoping for the best-case scenario, but given Aishy's history and the situations he's had in the past, he could miss more than two. That's the unpredictability with concussion. 

"The AFL has set out a really strong protocol for players to return and Aishy, like all players who return, will have to step through each of those and tick each of those boxes off."

Longmuir said he was reluctant to comment on Mansell's Tribunal case given he did not follow it closely, but the coach expected there would be ongoing frustration as players adjusted to new expectations around head high contact.      

"We are asking our players to make split second decisions and sometimes they're going to get those decisions wrong," he said. 

"I think overall, the AFL's mantra of protecting the head is right and as we try and reach a water level where it's acceptable in our game there is going to be some frustrations around players getting suspended or free kicks against. 

"We're just going to have to deal with those frustrations until we find the right level."

The Dockers expect to have veteran forward Michael Walters available for a full game this week after he returned from a calf injury as the substitute against Richmond, while in-form ball-winner Jaeger O'Meara returns from suspension.

Darcy trained with the main group for periods on Wednesday but has been ruled out for Saturday's clash at Giants Stadium. 

Serong, who has managed an ankle issue since the Dockers' win against Geelong in round 10, finished Wednesday's session early and walked laps before doing some testing with trainers. 

Forward Michael Frederick is also managing an ankle niggle but is expected to play. 

With Darcy expected to return against Essendon in round 15, Longmuir suggested young star Luke Jackson would again carry the ruck against GWS, with support from Josh Treacy. 

How the Dockers cover for their absence in the forward line, however, would be an issue, with forwards Tom Emmett and Josh Corbett presenting as options this week.  

"The ruck combo was competitive on the weekend, I thought Jacko competed really well, followed up really well, and I thought Josh Treacy gave us a really good contest in there," Longmuir said. 

"He lacks a bit of height for a true ruckman, but he lacks nothing in the way he competes and follows up at ground level. 

"I didn't think that was our biggest issue in the game. How we complement our forward line will be a discussion at selection."