IT WAS the day the Demons proved to themselves they were a premiership contender.

Heading west in round 22 searching for their maiden top-eight scalp for 2018, Melbourne swamped West Coast early before holding on to book its first September campaign since 2006.

"Certainly, the belief built off the back of that game, there's no question," coach Simon Goodwin said three weeks later, following the elimination final win over Geelong.

"We'd played in a lot of games where expectation was high, and we'd probably fallen short at times."

The Demons lived up to every expectation on that 24-degree day in the west, similar conditions to those they'll face on Saturday with a Grand Final berth on the line.

Jake Melksham booted four goals, Max Gawn dominated the Eagles' ruck duo, James Harmes claimed Luke Shuey's scalp and Angus Brayshaw showed he's a big-time performer.

Jack Darling lasted just 10 minutes before he was ruled out with concussion, with the Eagles also missing key forward Josh Kennedy with a leg fracture.

The pair, who starred when it counted in the Eagles' qualifying final win over Collingwood, have already forced a change from the last Demons' meeting, with the bigger Joel Smith replacing Bayley Fritsch.

Oscar McDonald started on Darling before moving to Nathan Vardy, while Sam Frost will have been studying tapes of Kennedy all week ahead of their likely match-up.

Darling and Kennedy will cause headaches, but only if the Demons' midfield can't repeat what it did en route to the 17-point win in the penultimate match of the home and away season.

Contending with Scott Lycett and Vardy, Gawn put the ball on the platter for his midfield, even without Jack Viney, who will play his third consecutive game on Saturday.

Amassing 19 hit-outs to advantage, Gawn almost doubled the Eagles' count (10), leading to a 43-29 clearance win as West Coast scrambled for avenues to goal.

Darling's injury caused structural changes at both ends. All Australian intercept defender Jeremy McGovern swung forward for the first and second terms to provide a presence in attack.

Melksham, initially set for the job on McGovern, watched on as his opponent moved to the other end, with the Demons kicking the first four goals to silence the 55,824-strong Eagles crowd.

When the Eagles settled, small forwards Willie Rioli and Liam Ryan provided the spark.

Rioli finished the match with three goals, and a tantalising battle with Demon Neville Jetta is set to resume on Saturday.

Rioli's highlights reel included a soccer on the goal line, but it wasn't all one-way traffic, with Jetta's big tackle on Rioli into half time a big boost for the Demons.

The Demons jumped 27 points clear after half-time, only for the Eagles to kick four on the trot, both sides going goal for goal before the final break.

With Melbourne leading by eight points, Jake Melksham kicked the first of three final quarter majors before the Eagles edged ahead through Mark Hutchings, Rioli and Mark LeCras.

The veteran LeCras outmarked Fritsch to put the Eagles clear in a moment that may have flashed back in Simon Goodwin's thinking this week when making the tough call to drop the first-year swingman.

Melksham then ran into open goal, leading Eagles defender Tom Barrass to the ball in a passage Adam Simpson would've gone to the tape on in this week's build-up.

Half-forward Dean Kent kicked the sealer before Melksham capped off a day out.

While the Eagles will be buoyed by the return of their twin towers in the absence of defensive general Brad Sheppard, the win 34 days ago changed the Demons' perception.

For so long they headed west with little hope, losing 17 consecutive games from 2004-2016 including a 2006 semi-final to Fremantle.

This time around they've got 16 of the 22 who beat the Eagles at Subiaco in 2017 and almost the exact team from this year's triumph at Optus Stadium.

And they've got the confidence, the routine, the belief, the ability and the momentum to get the job done.

Changes from round 22

West Coast

IN: Will Schofield, Josh Kennedy
OUT: Brad Sheppard (hamstring), Brendon Ah Chee (omitted)

Melbourne

IN: Joel Smith, Jack Viney
OUT: Bayley Fritsch (omitted), Dean Kent (AC joint)