FREMANTLE forward Chris Mayne says his team cannot afford to slip away from its best football against West Coast in Saturday's Derby if it wants to continue a month-long winning streak.

Sunday's 27-point win over Port Adelaide at AAMI Stadium was Freo's fourth in succession, but the four points were tarnished by a final-quarter fade out that saw the Power win the last term by 17 points.

Mayne said the football Fremantle produced in the first half, restricting Port to just 1.3, was good enough to challenge the AFL's best sides. 

But he warned the team would not get away with another fadeout against a West Coast outfit that was ruthless in dispatching the Brisbane Lions by 98 points on Sunday.

"If we slip a little bit, then quality sides like West Coast can really damage you," Mayne said on Monday.

"Against a top side like that, you really do have to play four quarters.

"The last month has been our best footy. We've played the way we've wanted to play in glimpses and it has been nearly four-quarter efforts in most games.

"It's going to be a challenge for us to really produce that form and keep it going. Hopefully momentum will stay with us and we can keep getting wins on the board."

Captain Matthew Pavlich called Fremantle together on-field at the end of Sunday's win and asked his teammates what they had expected out of the game. 
 
Mayne said it had been a chance for the players to reiterate that they want to produce the football they played in the first half every week.

"A few players got to say a few things, basically around those lines … we were a little bit disappointed in the way we finished the second half.

"Keeping the ball in our forward half, re-entries and scoreboard pressure is what we expect."

Fremantle has lost its last three clashes against West Coast, including a 48-point defeat in round nine this season that saw the team kick just five goals.  

The Eagles could be without captain Darren Glass, who was reported for rough conduct against the Lions, as well as senior stars Daniel Kerr (hamstring tightness) and Dean Cox (ankle), who need to be assessed this week.

However, Mayne said the Eagles would be a challenge on Saturday regardless of personnel.

"It'll definitely be a battle," the sharpshooter, who has kicked 31.3 this season, said.

"They've got the last three over us and this time in front of our fans it's important for them to get one back.

"[The Eagles] have shown over the year that they should never be doubted, no matter who's in the side. They've got great depth.

"For us as a forward group it'll be back to the basics of what we expect of each other to really challenge them as a backline and them as a side."

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Vote for Chris Mayne Mark of the Year
Lyon: Carlton Mid Derby one of the "nation's great rivalries"
From the Eagles: Glass accepts ban
Lyon lauds Pearce's hard work
Fyfe's a monster athlete: Lyon
Five Talking Points from round 18 v Port
We're ready for Eagles says Barlow
From the Eagles: Three Ds in doubt for Derby

Nathan Schmook covers Fremantle news for AFL.com.au. Follow him on Twitter: @AFL_Nathan