West Coast has snatched an epic qualifying final victory and broken Collingwood hearts after downing the brave Magpies by 16 points in a classic contest at Optus Stadium on Saturday night.

After trailing the visitors by 10 points at three-quarter time, the Eagles stormed home, inspired by some brilliance from twin towers Josh Kennedy and Jack Darling, to book a home preliminary final for the first time since 2015.

West Coast booted five goals to one in the fourth quarter, running over the top of an under-siege Collingwood, despite losing vital defender Brad Sheppard to a potentially season-ending hamstring injury in the first term. 

In an unforgettable final at WA's new football mecca, the Eagles' most experienced September campaigner Lewis Jetta was the hero, snapping a brilliant major with just over five minutes on the clock to put them ahead by four points.

It was the 11th lead change of drama-packed encounter, and when Darling kicked his second goal soon after, the home side had done enough. 

At the final siren, Jack Redden sent the record 59,585-strong crowd into raptures by slotting his set shot, ensuring the Eagles ran out 12.14 (86) to 10.10 (70) winners.

"The game itself was pretty hot for most of the night. We made some mistakes, they made some mistakes," a relieved West Coast coach Adam Simpson said post-match.

"The last quarter I thought we stood up in the contest and our leaders stood up. Kennedy and Darling in the front half, and the contest was probably an indicator the whole night what was happening.

"When you're 10 points down at three-quarter time, I think two things really helped us – one was our crowd, and two was our leaders,

"I thought the boys stood up around the contest in the last."

The margin didn’t do justice to the match, which ebbed and flowed from the opening bounce.  

Collingwood reclaimed the lead by two points at the 17-minute mark of the final term after Jordan De Goey slotted a clutch goal, and will be shattered after taking it up to West Coast with a frenetic, high-pressure game style.

The Pies are now facing a cutthroat semi-final at the MCG against Greater Western Sydney, while the Eagles can sit back over the weekend off and await the victor of Hawthorn's do-or-die clash with Melbourne.

It had been a fizzer of a finals series until Saturday night's bout, but West Coast and Collingwood more than made up for it with a thrilling and absorbing clash.

The Eagles had all the momentum early, with finals debutant Liam Ryan overcoming early nerves and drilling two majors to hand the home side an 18-point break in the first term. 

But Travis Varcoe, whose sister Margaret passed away last week, inspired the Pies with a deadeye finish from 50m out near the boundary before the break.

Varcoe was swamped by his teammates after his superb finish, and after resetting at quarter-time, Collingwood got the game on its terms in the second quarter.

West Coast hasn't lost a game all year when taking more than 90 marks and piled up 33 by quarter-time, with star defender Jeremy McGovern pulling in seven of his own.

However, the Pies soon turned the game into a ground-level battle and took a three-point lead into half-time with a six-goal-to-three second term. 

The third quarter was almost unbearable, with both sides missing some golden opportunities in front of goal. 

There was no bigger culprit than returning star Kennedy, who missed three shots before finally finding the major opening.

The rusty dual Coleman medallist was superbly held by Tyson Goldsack in his miraculous comeback game from a ruptured ACL only six months ago, but found some form in the second half and finished with two majors.  

The Pies rolled the dice at the selection table, but gun midfielder Adam Treloar (24 disposals) was outstanding in his comeback from a rare double hamstring and defender Jeremy Howe contained Darling until the final quarter.  

Collingwood's All Australian duo Brodie Grundy (48 hit-outs, 18 disposals) and Steele Sidebottom (27 disposals, five clearances) were brilliant turning the tide after quarter-time, with strong support from Taylor Adams (26, two goals), Tom Phillips and Brayden Sier (26).  

Elliot Yeo (36, nine inside 50s) was the Eagles' best four-quarter performer in a midfield which matched the Pies for clearances (36-37).

The Eagles won contested ball (169-163), with Dom Sheed (27, one goal), Luke Shuey (19) and Redden (32, one goal) stepping up in the second half to help send the Eagles through to the preliminary final.  

While West Coast breathed a massive sigh of relief at the final siren, Buckley was left lamenting losing contested possessions 32-46 in the tense last quarter, after having an edge most of the night.

"We gave up some momentum at stoppage and got done at contested ball. That's where finals games largely exist," he said.

"We thought we were able to handle it for the most part, and we were in a position at three-quarter time to go ahead and finish the game off, but we didn't. 

"The opposition, you've got to give them credit for their persistence and what they were able to do out of stoppage. 

"We were well beaten in contested ball in that last quarter and put our backs under a fair bit of pressure as a result."  

MEDICAL ROOM
West Coast: Crucial Eagles defender Brad Sheppard looked to suffer a bad hamstring tear entering time-on in the first quarter after trying to soccer the ball off the ground. He needed assistance hobbling from the ground and his season looks to be over. West Coast small forward Willie Rioli was split open by a head clash with Levi Greenwood late in the final term. He needed stitches but will be fine for the preliminary final. 

Collingwood: Midfield star Taylor Adams had to be helped by trainers early in the final term after copping Elliot Yeo's knee to his head, but he was soon back in the action.

WEST COAST           3.3     6.7    7.11   12.14     (86)
COLLINGWOOD     1.3     7.4     9.9     10.10     (70) 

GOALS
West Coast: Ryan 2, Darling 2, Kennedy 2, Vardy, Jetta, Sheed, Cripps, Rioli, Redden
Collingwood: Adams 2, De Goey 2, Mihocek 2, Stephenson, Thomas, Varcoe, Mayne

BEST 
West Coast: Yeo, McGovern, Ryan, Jetta, Sheed, Redden
Collingwood: Sidebottom, Adams, Grundy, Goldsack, Treloar, Mihocek

INJURIES 
West Coast: Sheppard (hamstring)
Collingwood: Nil 

Reports: Nil
Umpires: Nicholls, Meredith, Harris  
Official crowd: 59,585 at Optus Stadium