The Dockers enter Saturday night's western derby desperate to atone after coughing up late leads against Carlton and Port Adelaide over the past fortnight.

Those losses means Fremantle are now back with the pack at 3-2, but Longmuir hopes the lessons learned will prove invaluable down the track.

"I've been really impressed with the way the players have owned our part in those two losses," Longmuir said.

"We need to learn from them and get better from them, because if we're in that position in big games down the track, we want to be able to execute better than what we did."

Fremantle have been the league's best defensive side across the first five rounds, conceding just 63.8 points per game.

But they are ranked 12th in attack after being restricted to an average of 78 points per match.

The return of ruckman Sean Darcy is expected to give Fremantle a scoring boost, given it will free up Luke Jackson to join Jye Amiss and Josh Treacy in attack.

Longmuir wants his team's scoring output to increase.

"Really, when you talk about bang for buck over the last couple of weeks (it's about) making more of the opportunities we're creating for ourselves," he said.

"Whether that's in the contest in our front half with one-on-ones, or just finishing off our work better in front of goal."

West Coast enter the derby on a high after beating an understrength Richmond by 39 points last week to post their first victory of the season.

The Eagles copped a 101-point thrashing at the hands of Fremantle in round 22 last year, but are expected to put up far more resistance this time around.

The barnstorming form of fit-again veteran Elliot Yeo and the rapid emergence of No.1 draft pick Harley Reid have helped turn West Coast's midfield from a weakness into a strength.

Yeo, Reid, Tim Kelly and Reuben Ginbey will battle the likes of Nat Fyfe, Caleb Serong, Andrew Brayshaw and Hayden Young in an intriguing midfield battle.

Fremantle have won the past five derbies, and are hot favourites to keep that winning streak going.

The Dockers' recent dominance has continued a trend in derbies.

West Coast won 11 in a row from 2015-21, with that run snapping a sequence of six Fremantle victories.

Not since 2015 - when Fremantle won the minor premiership and West Coast reached the grand final - have the teams been on an equal footing in terms of their premiership window.

"In my time there's been different phases that both clubs have been in,'' West Coast coach Adam Simpson said.

"The closest time when it was neck-and-neck was around 2015, so it's been a bit lopsided the last (16) times we've played."

Australian Associated Press