Fremantle ruckman Aaron Sandilands will miss the rest of the season after suffering a serious hamstring injury in his comeback game against St Kilda.

Sandilands grabbed his right hamstring after tackling Saints defender Sam Gilbert in the first quarter of Sunday's nine-point loss, and immediately hobbled from Domain Stadium.

The 34-year-old was returning after missing the Freo’s previous four defeats due to hamstring tendon inflammation in the same leg.

Speaking post-match, coach Ross Lyon dismissed concerns that Sandilands had been brought back too early and refused to blame losing the influential 211cm big man for the defeat.

"It's season-ending, so that's the end of Aaron for the year, but that's no excuse – they lost Gilbert (to concussion)," Lyon said.

"Teams are losing two and three (players in-game). You've got to have the fortitude, desire and mental toughness to get it done.

"I haven't checked-in with (Sandilands). I just gave him a tap on the bum.

"He's a pretty tough character, it's just the environment we're in, stuff happens."

Sandilands, who recently re-signed to play on in 2018, has had a wretched run with injury over the past two seasons after showing remarkable durability throughout his illustrious career.

He was sidelined for most of last year after sustaining broken ribs when Nic Naitanui planted a knee in his back in a marking contest during the round three Carlton Draught Derby, and only returned in round 20.

The silver lining for Fremantle is the impressive form of second-gamer Sean Darcy, who backed-up his strong debut effort against Geelong with another 33 hit-outs, 16 disposals and his first career goal against the Saints.

"He clearly competes, doesn't he? He's got some attributes that we like and he's working hard," Lyon said.

"He's got plenty in front of him, plenty of growth."

But, after shanking a last-gasp shot to sink Geelong last round, Michael Walters was the star for Freo, booting a career-best six goals and picking up 32 disposals in a dominant display.

"It was pretty handy, wasn't it? He's a remarkable young man in the way he applies himself and he gets reward for his (effort)," Lyon said.

"He's making the most of his God-given talent. More of him would be nice."

Fremantle hope to regain Stephen Hill from a minor calf strain ahead of a looming clash with North Melbourne, while youngster Connor Blakely will be available after a club-imposed suspension.

Blakely was banned after leaving the club early on Wednesday and then travelling to Yallingup and going surfing.

"It was counter-intuitive when you've got some illness and then you're surfing," Lyon said.

"There was plenty of good performances, so if you give up your spot there's no guarantee you come back in.

"Yeah (he'll be available), as long as he prepares in the manner we prescribe."

Fredo’s fifth-straight loss was a hammer blow to their finals chances, with Freo slumping to 6-8 and 14th spot on the ladder.

"The finals take care of themselves. You've got to win. You can't hope your way into finals and dream it," Lyon said.

"But where we're at, the overriding (requirement) is that we compete and we improve and we expose our list and I think we're doing that on all fronts.

"No-one can criticise us for not having a dip today or last week."