WEST Coast coach Adam Simpson believes his players' invaluable finals experience was a decisive factor in the Eagles' stunning fourth-quarter surge against Collingwood, which catapulted them into a second home preliminary final in four seasons.

A man down after Brad Sheppard's hamstring injury, the Eagles were staring down the barrel at three-quarter time of the qualifying final when they trailed the frenetic Pies by 10 points.

But spurred on by a massive 59,585-strong crowd at Optus Stadium, West Coast lifted in a pulsating final term, booting five-goals-to-one to clinch a famous 16-point triumph.

EAGLES SOAR INTO PRELIM Full match coverage and stats 

With the game on the line, the Eagles dominated the contest (46-32) and Simpson praised his leaders, in particular, for stepping up.

West Coast had 18 players with finals experience (133 games), compared to the Pies' eight (77 games) and Simpson thought that told part of the story when the match was at its hottest.

"We've been here before, so the experience of our players really shone through tonight," Simpson said post-match.

EVERY EAGLE RATED How did they perform?

"I don't know how many players for the Pies had played in a final, with the opportunity to get into a prelim, but we've been there before and I'm sure at some stage we would've drawn upon that.

"That being familiar to us – and we've been in the finals for four years now and made a couple of prelims – so I'm hoping the maturity of our players means we're more ready than we were in '15."

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After struggling to get off the leash all night, West Coast tall forwards Josh Kennedy and Jack Darling inspired the Eagles in the final term, both booting clutch set shot goals. 

But former Swans speedster Lewis Jetta, the most experienced Eagle in finals, was the hero, and brought the house down with his sublime snap which snatched West Coast the lead back with little more than five minutes to play.

"He had some really good moments, Jetts, and some moments with the ball that we questioned in the box, but I think we've got to accept that, because when he stands up (is important) and what he's done as an individual this year, he's a real leader amongst the Indigenous players at the club," Simpson said.

"I saw him after I spoke at three-quarter time get the boys in and talk about what they were going to do as a unit.

"I thought Liam Ryan (two goals) and obviously Willie (Rioli) really stood up in the last as well.

"For a game that big, for those boys to produce some of the bigger moments was really pleasing."

WATCH Adam Simpson's full post-match press conference

The Eagles have two weeks to prepare for either Hawthorn or Melbourne in the preliminary final, and will be sweating on Sheppard's scans, although his September looks to be over after a nasty hamstring injury.

Versatile backman Will Schofield is the leading contender to return in his place, although dashing half-back Jackson Nelson is another option.

Aside from Sheppard, the Eagles escaped without any other injury worries and Kennedy got through his first game since suffering a hairline fracture in his shin at training following round 18.

The dual Coleman medallist dropped numerous marks and looked rusty for most of Saturday night, nearly costing West Coast with three missed shots early in the third quarter.

But the champion forward ended with two majors after an absorbing duel with Tyson Goldsack in his first game back only six months after a knee reconstruction.

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"He (Kennedy) was defended really well. We all ask questions about bringing these players back off no form, but when they're doing a job like that (it is worthwhile)," Simpson said. 

"I thought JK had 10 opportunities in the first three quarters and it took him until the last to get into the game in the way he knows he can do.

"I thought he was part of our resurgence in the last along with all of our leaders."