West Coast skipper Darren Glass is confident Eric Mackenzie's costly howlers in last week's AFL loss to St Kilda won't leave the fledgling defender mentally fragile in Sunday's western derby against Fremantle.

Mackenzie twice turned the ball over deep in defence through horror kicks, late in the loss to the Saints, with the subsequent goals killing off any chance of an Eagles' victory.

It was an unfortunate end to the game for Mackenzie who, up until that point, had played a terrific shutdown role on danger forward Nick Riewoldt.

Mackenzie is in line to get the job on Fremantle captain Matthew Pavlich in what shapes as a crucial derby match-up, and Glass is adamant the 23-year-old's mistakes against the Saints won't come back to haunt him.

"Oh look, Eric's a terrific player. I've told him time and again that he's well and truly advanced on where I was at that age," Glass said on Monday.

"To hold Nick Riewoldt to one point is a big effort.

"He played a great game.

"Down back, mistakes are magnified. You can do a simple spoil down back and it can look great, or mess up a kick and it can look poor.

"We all make mistakes every game.

"No one's played the perfect game. He'll bounce back.

"I know that he does a lot of work on his kicking and he'll be fine.

"He has to move on pretty quick."

With West Coast still pushing for a top-four berth and Fremantle looking to cement their spot inside the top eight, the derby promises to be a big one.

Glass urged his teammates not to get sucked in by any Fremantle mischief, especially that conducted by chief antagonist Hayden Ballantyne, who won several free kicks against the Swans on Sunday after his niggling antics resulted in Sydney players lashing out.

"It's important not to let anyone get under the skin, not just Ballantyne," Glass said.

"We gave away a couple of free kicks on the weekend which resulted in goals, so Woosh wasn't too happy about that, so I'd be surprised if anyone does it this week.

"I haven't played on Ballantyne too much but I think he does it more just to get himself up and about and, if that's the way he plays the game, best of luck to him.

"It's not too often where both sides have been in the top eight, not that I can remember, so it should be an interesting game.

"We want to finish as high on the ladder as we can. We want to keep pushing for a top-four spot so it's a big game. If we can push another challenger down, that's all the better."

Gun Eagles' midfielder Daniel Kerr, who missed the loss to St Kilda due to general soreness, is a strong chance to return against the Dockers, while Fremantle ruckman Aaron Sandilands (toe) and defender Nick Suban (leg) will push their cases for recalls later this week.

Brought to you by AAP © 2024 AAP