IT WAS a Demon dismantling beyond West Coast's wildest dreams – a 66-point preliminary final thumping of Melbourne that has powered the Eagles into a Grand Final showdown against Collingwood.

In a performance that nobody saw coming, the Eagles brutally ended Melbourne's fairytale September run with a 18.13 (121) to 7.13 (55) hammering that will haunt Simon Goodwin's men, the AFL's highest-scoring team which didn't kick a goal before half-time.

Only five weeks ago, the Demons stormed the Eagles' Optus Stadium fortress and got their season rolling with a blistering 17-point triumph.

It ignited a finals charge that many believed could deliver Melbourne a drought-breaking flag for the first time in 54 years.

But the red and blue faithful will have to keep waiting after a Perth horror show that re-wrote the record books.

Melbourne's goalless opening half was the first by any team in a final since 1927, first-ever in a preliminary final, and their 0.6 scoreline was the lowest finals score at the main break since 1960.

Meanwhile, the Eagles slammed on 10 goals unanswered majors, heading to the rooms to rapturous applause from a ferocious 59,608-strong crowd, a new WA sporting record.

It took until the opening minute of the second half for Clayton Oliver to finally find the major opening, and the Demons at least stemmed the bleeding in the second half after trailing by 63 at the major break.

But there will be little solace for the visitors, who arrived in Perth brimming with confidence and failed to fire a shot.

The Demons fumbled and bumbled from the opening siren, routinely botching simple handballs, slipping over and missing targets by foot.

When their most experienced big-game player Jordan Lewis floated a shocking handball deep in defence after five minutes, allowing Josh Kennedy to intercept and snap the opening goal, the signs weren't looking promising, and it didn't get better.

"It didn't look like us in any phase of the game," Goodwin said post-match.

"We made a lot of mistakes early and our turnovers cost us greatly. 

"In terms of what we really pride ourselves on as a footy club, we had 34 tackles for the day and lost the contested ball (159-144).

"It's not the game you want to lose those stats. That was the more disappointing part."

But everything went right for West Coast, from Mark LeCras' fluky back-heeled goal in the second stanza to Jack Darling's miracle dribbling left-footer from outside 50 in the third quarter.  

However, luck had little to do with the end result. This was red-hot football by West Coast in an Optus Stadium cauldron packed to the rafters on a warm spring day.

The Eagles couldn't have been slicker, or tougher against the competition's best contested team.

Only inaccuracy – they booted 4.8 to 0.3 – an overruled LeCras major and free-kick denying Liam Ryan's goal kept Goodwin's outfit in the contest by quarter-time, and the Demons couldn't muster a response against a West Coast side which, surely now, commands respect.

Despite finishing second on the ladder, boasting a 3-1 record against the other preliminary final teams and 10-3 record at home, West Coast still hadn't won over many doubters, especially in midfield. 

But the Eagles' onballers outhunted Melbourne, while Scott Lycett and Nathan Vardy totally nullified Melbourne giant Max Gawn in the ruck. 

At least breaking even in the middle was West Coast's simple focus, but Jack Redden (31 disposals, one goal), Dom Sheed (27), Elliot Yeo (23) and Luke Shuey (21) gave the Demons' young engine room a lesson.

Tagger Mark Hutchings was surprisingly sent to Demons bull Jack Viney (21 possessions), and kept the inspirational co-captain quiet, while young stars Angus Brayshaw (29) and Clayton Oliver (26) barely had an influence.

Talismanic West Coast spearhead Kennedy, who missed the round 22 bout, feasted on the lightning-fast ball movement and toweled up Sam Frost.

The dual Coleman medallist booted four goals – including two in a minute to start the second quarter after the Eagles' initial four-goal burst – and held seven marks, showing no signs of the rust which plagued his qualifying final performance against the Pies.

West Coast's record with Kennedy and Darling (three goals) in the same line-up this season has now improved to a flawless 12-0, and the twin towers will give Nathan Buckley and his coaching staff headaches ahead of the Grand Final.

But the Eagles are just as dangerous at ground level, with Jamie Cripps (three), Mark LeCras (three), Liam Ryan, Willie Rioli and Daniel Venables (one each) combining for nine majors.

At the other end, only Jake Melskham (two goals) – the hero last time with four majors - managed multiple goals on a dark day for a success-starved club, whose Grand Final drought will extend into a 19^th year.

But the Eagles will enter their second Grand Final in four seasons full of belief, keen to right the wrongs of 2015 and ready for the most unexpected of deciders against a Collingwood side similarly written-off as even a finals contender before the 2018 campaign started.

MEDICAL ROOM
West Coast: Jeremy McGovern sent major concern through the camp when he came off midway through the first term and went to the rooms, sparking fears of a concussion test, but he was back on the ground within minutes. He will be monitored this week but shouldn't have any dramas getting up for the Grand Final. The Eagles stunning start was tempered by a left ankle injury suffered by star midfielder Luke Shuey early in the second term, but he was soon back in the action after a quick trip to the rooms and played out the game without any issues. They otherwise seem to finish with a clean bill of health.

Melbourne: The Dees seemingly got through without any injuries.

NEXT UP

The Eagles are into their seventh Grand Final and have seven days to prepare to face Collingwood in the decider, while Melbourne will head for exit interviews and a post-mortem that will be tough to sit through.