West Coast has wasted little time getting over its first loss of the AFL season, quickly turning its attention to building a new winning streak starting with Port Adelaide on Sunday.

Collingwood caused one of the upsets of the season when it beat the previously undefeated Eagles by 23 points at the MCG last Saturday.

It was the first time in eight years that the bottom club had knocked off a ladder leader.

West Coast coach John Worsfold admits his team "let its guard down" against the Magpies, but dismissed it as a one-off rather than a cause for concern.

"After so many weeks of playing really good football, there are weeks when you do let your guard down a bit," he said.

"I think we may have had small periods of that previously, but had still been good enough to hold on and win.

"This time we weren't good enough."

West Coast led by two goals at quarter time against Collingwood and again enjoyed a narrow lead at the last change.

But rather than running over the top of the struggling `Pies, it was Mick Malthouse's team that came to life, piling on seven goals to two in the final term for a morale-boosting victory.

Worsfold admitted he had noticed a lack of intensity with some of his players after West Coast's impressive eight-game winning streak to start the year.

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