Fremantle coach Ross Lyon says he’ll give Zac Dawson one last chance to prove his fitness on Thursday before deciding whether he’s fit enough to play in Saturday’s AFL clash with Port Adelaide at Adelaide Oval.

Dawson was reduced to crutches after injuring his ankle during Sunday’s western derby win over West Coast.

With Luke McPharlin (quad) already ruled out this week, the Dockers are desperate to have Dawson available.

Dawson failed to train with the main group on Thursday, but Lyon said the former Saint would be assessed behind closed doors.

“He spoke to me downstairs. He’s still working through recovery,” Lyon said on Thursday.

“He’s saying he still wants to have a go. So we’ll give him every possible chance and we’ll see what that looks like.”

Alex Silvagni will replace McPharlin, while forward Chris Mayne is likely to play in defence if Dawson fails in his bid to recover in time.

Fremantle’s defensive injury woes come at a terrible time given Port Adelaide’s attacking potency.

Spearhead Jay Schulz leads the Coleman Medal race with 24 goals, while 199cm Justin Westhoff and All-Australian Chad Wingard also pose major threats.