FREMANTLE'S star-studded midfield has led the Dockers' stunning revival, but skipper Nat Fyfe and the entire engine room still has plenty of room for improvement, according to coach Ross Lyon.

Experienced campaigners Fyfe, Stephen Hill, giant ruckman Aaron Sandilands, plus Lachie Neale and David Mundy – who have both spent significant time forward – have sparked Freo's turnaround after a disastrous 0-2 start. 

The Dockers have outhunted reigning premiers the Western Bulldogs and Melbourne in consecutive weeks, displaying the type of pressure that Lyon-coached teams have long been associated with. 

But with Fyfe, averaging 29 touches and nearly a goal a game, still building in his return from a broken leg - and the Dockers' younger onballers still developing - the Freo coach is excited by what lies ahead. 

"Nathan's effort at times has been supreme, but he's far from playing his best footy," Lyon said. 

"I thought (Melbourne ruckman Jake) Spencer had his moments around the ground against Aaron. 

"So I think there's plenty of upside in our midfield, we're nowhere near (our best).  

"I've seen our midfield play a hell of lot better than they are at the minute and more consistently over four quarters, so I think there's real upside in what we're doing.

"I've got no doubt about that." 

After enjoying success with a smaller and more mobile line-up, Fremantle is weighing up extra aerial support to combat North Melbourne' tall forward line, and likely ruck duo Todd Goldstein and Braydon Preuss.

But Lyon is tempted to stick with key defender Michael Johnson as a back-up to Sandilands, instead of recalling Jonathon Griffin.

"When you've got momentum and an equilibrium and balance in how you're playing, you like to stick with it, unless you're really forced to deviate," he said.

Stephen Hill (corked leg) and sore forward Michael Walters are expected to be fit for Saturday night's clash at Domain Stadium against winless North.

Lyon warned the Dockers against complacency against the Roos, who have been competitive and blew sizeable second-half leads against Geelong and the Bulldogs.

"We know psychologically that can happen, but our boys are really of an understanding … that North are formidable and it's going to be a tough assignment," he said.

Meanwhile, the Dockers are yet to reveal any decision about punishing Harley Bennell.

The 24-year-old was intoxicated and asked to leave a flight from Melbourne to Gold Coast shortly after boarding last Saturday, while he was on club-approved leave following his latest calf setback

"I'm certainly not here to punish and have retribution – that's not how I live – but I understand there's others that are doing their job and all those things," Lyon said.

"Obviously we can support until we can't.

"There's nothing here that dictates no support for Harley, so let's just be clear on that."