West Coast coach Adam Simpson reckons Friday night's grand-final rematch will be his team's toughest test to date despite Collingwood's poor recent form.
But the Eagles will have to confront the challenge without premiership defender Liam Duggan, who has been ruled out of action for up to six weeks with an ankle injury.
The Magpies have dropped off significantly over the past three weeks, with their inconsistent efforts raising the ire of coach Nathan Buckley.
Collingwood followed an unconvincing nine-point win over the Bulldogs with a shock 44-point loss to North Melbourne.
Last week's upset four-point defeat to Hawthorn raised further doubts about Collingwood's premiership credentials, and they could drop to fifth on the ladder if they lose to the Eagles.
In contrast, West Coast will enter Friday night's blockbuster at Optus Stadium oozing confidence following their 91-point demolition of Fremantle.
The Eagles have won four straight against the Magpies - including last year's epic grand final.
Despite that strong record and Collingwood's recent form wobbles, Simpson is bracing his players for a fierce test.
"They had a bit of a blowout (loss) two weeks ago, just like we had a blowout three weeks ago," Simpson told Seven Network.
"So I don't see the same sort of concerns (with Collingwood) as perhaps everyone else.
"I feel like every team goes through some form slumps, but the fact is they've been winning for most weeks.
"We look at it as probably the biggest challenge of the year this week."
West Coast can open up a two-match gap on Collingwood if they win.
A loss would mean the Magpies join West Coast on 11 wins, which would create a fierce race for second spot.
Simpson said forward Josh Kennedy, who missed the derby win with a cold, would return against Collingwood.
But Duggan has been ruled out for at least five weeks with the high ankle sprain he suffered in the opening term of the western derby win.
Ruckman Nathan Vardy is three weeks away from returning from a knee and ankle injury, while Mark Hutchings (hamstring) will miss another two weeks.
Meanwhile, Simpson wasn't overly fussed by the Harry Highpants joke from Jeremy McGovern and Tom Barrass following the western derby win.
The star defensive duo pulled their shorts up high while posing for the official derby-winning photo with their teammates.
"I was in that team photo and just before that photo was taken Luke Shuey said, 'Nothing silly boys'. Clearly Gov and Barrass weren't listening," Simpson said.
"There's a fine line isn't it between a bit of humour and respecting (sponsor) RAC and the derby. It's a fine line, but I think it was in good humour."