ADAM Simpson admits a flat West Coast ran out of steam against an under-pressure Collingwood outfit which wanted the win more in Friday night's thrilling one-point defeat that has thrown the top-four race wide open again.

After trailing by 16 points at the final change, the Pies stormed home in a dominant final term at Optus Stadium, outhunting the Eagles around the ball (+22) and commanding field position (20-5 inside 50s).  

West Coast managed only a single point in the fourth quarter, while the Pies booted 2.6 and had the Eagles backline under siege. 

"It would have been a pretty good game to watch. I think there was probably three or four chapters within that game that ebbed and flowed," Simpson said.

"We just ran out of steam in the second half, really. Their ability to sustain effort was better than ours. That was pretty much what it came down to.  

"In the last quarter we couldn’t win the ball. We couldn't get any field position.  

"They just looked like they wanted it a little bit more than we did at stages. 

"We did look flat, didn't we, in the last quarter. We'll have to look at it. But I dare say it was a by-product of how good Collingwood looked."

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The Eagles had won the past four over Nathan Buckley's men and could have moved two wins clear in second spot if they had held on.

But their second loss in 10 games has shuffled them down to third spot and the race for a home qualifying final has been blown wide open.

Collingwood had been under the pump all week after losing two on the trot and the overflowing of emotion at the final siren showed how much the win meant to the visitors.

"To beat a team the last four or five times, to beat them in a Grand (Final), it gets to that point where they're probably saying 'enough's enough' and we need to recognise that and respond, which we have before, but we just didn't tonight," Simpson said.

"I'm not going to go to angry at the players. I think they've been putting up pretty good effort for most of the year.

"The last quarter was really disappointing. I won't be saying 'it's unacceptable and we need to get better'.  

"We got outhunted in that last quarter and it's something we've got to redeem." - Adam Simpson

The Eagles lost small forward Jamie Cripps to an adductor injury in the first term, putting their rotations under pressure with Nic Naitanui on limited minutes.

Naitanui tired late against Brodie Grundy, whose influence on the Pies' midfield was profound, while another A-grader, spearhead Josh Kennedy, had no impact and went goalless in consecutive games for the first time since rounds 21-23 in 2013.  

WATCH Adam Simpson's full post-match media conference

"I think he just got beaten tonight. He had his colours lowered. Individuals tonight who normally stand pretty tall for us were perhaps not at their best," Simpson said.  

"They'll recognise that. They're not robots, sometimes that happens.

"But we need our good players playing well."