Does smiling Brennan Cox hint to a late Dockers switch?

The two defenders are vying for one spot ahead of Saturday's AFL grand final against Brisbane at the MCG.

Cox hasn't played since injuring his calf in the final-round loss to Carlton on August 22, with knee soreness keeping him out for two matches a month earlier.

McDonald has filled in admirably in Cox's absence, but he copped a heavy knock from teammate Mason Cox in Fremantle's thrilling preliminary final win over Sydney.

Eyebrows were raised on Wednesday morning when a subdued McDonald entered the training arena in his tracksuit top, with a hug from a teammate following shortly after.

But McDonald took off the tracksuit top once he was warmed up and joined in at full training, even sharing a moment with Cox in the goalsquare at one point.

Cox, who was held out of Sunday's WAFL grand final due to the initial doubts surrounding McDonald, ticked every box needed at training to prove he is ready if coach Justin Longmuir hands him a dream recall.

Adding intrigue to the selection decision was the sight of McDonald looking sombre at times, while Cox looked relaxed and was all smiles while chatting to friends and posing for selfies with fans at the end of the session.

With music playing in the background and fans cheering on, Fremantle players were in an upbeat mood as they cruised through their paces early in Wednesday's training hit-out.

Captain Alex Pearce and retiring forward Sam Switkowski ran laps early before joining their teammates for full match simulation.

Cult hero small forward Isaiah Dudley received a huge cheer and waved to the crowd as he made his way to the boundary line during match simulation.

Fans went into overdrive as Fremantle's players signed autographs and posed for selfies after the session. 

Chants of "Freo, Freo" were heard as kids clamoured for autographs. 

The Dockers fly out to Melbourne on Thursday, with the grand final parade on Friday and the 'Big Dance' on Saturday.