The Eagles caught the home side napping in the opening quarter, generating 10 scoring shots to the Power's five to lead by 10 points at the first change.
The visitors, who were disadvantaged by having one less day's break between games than their opponents and also by having to travel, were - in theory - to tire as the match wore on.
However, the Eagles displayed resilience not evident in their wooden-spoon season last year and led from start to finish to record a 16.20 (116) to 15.8 (98) win.
The win was West Coast's first at AAMI Stadium since 2007 and first win over Port Adelaide at the venue in 13 years.
The Power were disappointing for the large part, lacking intensity and the willingness to chase opponents, including Andrew Embley (32 possessions and four goals) and Luke Shuey (27 possessions and three goals). The pair were allowed to run riot for much of the game.
The Eagles should've had the game won by three-quarter time, but left the door open for Port Adelaide with their inaccuracy in front of goal.
The home side rallied in the final term and closed to within five points, but goals to Embley and Shuey sealed the memorable win.
Embley and classy Power forward Robbie Gray, who kept his side in the contest in the first half, both finished with four goals each, while Josh Kennedy (three goals) and Mark Nicoski (two goals) chipped in to help fill the void left by injured All Australian Mark LeCras.
Substitute player Jason Davenport (three goals) and veteran Chad Cornes (two) were the only other multiple goalkickers for Port Adelaide.
The Power's second straight loss was compounded by a knee injury to skipper Dom Cassisi. Eagles vice-captain Beau Waters also came from the ground late in the game, after injuring his 'good' elbow.
The injury-plagued Daniel Kerr got through his first game back after a long layoff unscathed. Kerr started slowly, but worked his way into the match and finished with 25 disposals (10 contested) and four clearances.
Influential players
It was a vintage performance from Embley. The premiership player and Norm Smith medallist ignited the Eagles with 19 possessions in the first half and continued to have an influence even after Power tagger Kane Cornes went to him in the third term.
Gray threatened to win the game for Port Adelaide on his own in the first half, booting four goals. He was also used to great effect in the midfield, but coach Matthew Primus was eventually forced to use him exclusively in attack because he was the club's only viable goalkicking option.
What it means
Last year's wooden-spooners will maintain their spot in the top eight at the completion of the round. The Eagles covered the loss of LeCras by generating more goals from their midfield and showed they will be competitive this season.
The game against West Coast was a must-win for the Power, who will head to Skilled Stadium to take on Geelong next weekend without Cassisi. They now face the real possibility of being 0-4 heading into the game against Gold Coast in round five.
The next four
Port Adelaide: Geelong (Skilled Stadium), Adelaide (AAMI Stadium), Gold Coast (AAMI Stadium), North Melbourne (Etihad Stadium)
West Coast: Sydney Swans (Patersons Stadium), Hawthorn (Aurora Stadium), Bye, Melbourne (Patersons Stadium)
Dream Team highlight
Port Adelaide: Davenport didn't top score for the Power, but he racked up an impressive 55 points after coming on for the injured Cassisi at the start of the second half.
West Coast: Embley's dominance was reflected in his game-high Dream Team score of 155. Cox was brilliant again, with 118 points while Shuey (100 points) also proved good value for money.
What the coaches said
Matthew Primus (Port Adelaide):
"We got blown away early in the game…and we watched the ball a little bit. It was really disappointing and probably even more disappointing was to fight back [because the players showed] they actually had it in them to win the ball.
Our work rate and our ability to outwork the opposition with our legs was disappointing. We've got some youth in the team, but they've played enough footy to understand the intensity you need to keep playing at."
John Worsfold (West Coast):
"The belief within the group is a lot stronger. That belief in themselves that they're going to match it [with the opposition] and go out to win games even with LeCras out we weren't a lesser chance. We still wanted to win. It was a good start from Daniel Kerr today. His attitude about getting back to wanting to play his best footy has been great, but he's a long way back from where we know he can get to."
Key match-up
Dean Cox/Nic Naitanui v Dean Brogan
Cox was instrumental in the opening term, gathering seven possessions and eight hit-outs and the Eagles took the honours at the hit-outs (53 to 17) but Brogan was better than the statistics suggested. He was cannoned into at every opportunity, but battled manfully with little support. Brogan notched up an equal-game high seven clearances.
The crowd
Port Adelaide was hoping for a crowd in excess of 30,000 to help celebrate the recent merger with SANFL club Port Magpies. Mother Nature was unusually kind to the Power, turning on a great day for footy but only 23,214 people showed up to watch the teams play.
Saturday afternoon is traditionally regarded as a tough time-slot to fill in South Australia and the turnouts at AAMI Stadium both for the Power and also the Crows last weekend further highlight the challenges the two South Australian based AFL clubs are facing.
Port Adelaide: 2.3 7.3 12.4 15.8 (98)
West Coast: 3.7 9.10 12.16 16.20 (116)
GOALS
Port Adelaide: Gray 4, Davenport 3, C. Cornes 2, Cassisi, Brogan, Pearce, Boak, D. Stewart, Irons
West Coast: Embley 4, Kennedy 3, Shuey 3, Nicoski 2, Ebert, Darling, Lynch, Rosa
BEST
Port Adelaide: Boak, Gray, Broadbent, P. Stewart, Rodan
West Coast: Embley, Cox, Shuey, Rosa, Kerr, Priddis, Kennedy
INJURIES
Port Adelaide: Steven Salopek (hamstring strain) replaced in selected side by Jason Davenport, Cassisi (knee), Pittard (knee)
West Coast: None
SUBSTITUTES
Port Adelaide: Domenic Cassisi (knee) replaced by Jason Davenport at half-time, Paul Stewart (knee)
West Coast: Quinten Lynch replaced by Andrew Gaff in the third quarter
Reports: Nil
Umpires: Grun, Schmitt, Mollison
Official crowd: 23,214 at AAMI Stadium
The views in this story are those of the author and not necessarily those of the clubs or the AFL
