The Roos lost 10.12 (72) to the Power's 23.10 (148), and now has to wait to see if it can cling to fourth spot. If any of Adelaide, St Kilda or the Sydney Swans wins later in the round, North will face a sudden-death final next week.
The Kangaroos jumped out of the blocks with the first three goals.
Leigh Harding and Corey Jones booted the first two and when Daniel Pratt slotted one from inside the centre square it seemed as if North Melbourne’s good recent form would continue.
But they only booted seven of the next 30 as the Power ran away to a thumping win.
North Melbourne looked to have switched on in the second term, but the second quarter went on to mirror the first as once again Port hit back. The home side did their best to hold them off but relinquished the lead when David Rodan goaled with minutes remaining in the first half.
Compounding North Melbourne’s woes was the sight of Leigh Harding limping from the field in the first quarter.
Harding was treated for an injury to his left knee – the same one that was reconstructed two years ago this week, and did not take any further part in the day.
Harding was joined on the sidelines by teammate Daniel Wells who hobbled off with an ankle injury.
Wells returned in the second half but was clearly hampered by the injury and the close attention of Kane Cornes.
The Kangaroos were getting beaten in the stoppages in their back half and it showed on the scoreboard.
David Hale played like a man in career-best form but he had few friends in the blue and white.
The big man fought hard up forward and was a difficult match-up for the Port Adelaide backline. He finished with four goals.
Petrie got plenty of the ball, but was wasteful in front of goal, booting 0.3.
Coach Dean Laidley changed things in the second half, with Petrie taken out of the forward line and put in the ruck. But the shift could not stem the flow as the North Melbourne defence let through another eight goals in the third term to have the match all but over at the final break.
Rubbing salt in the wounds for Dean Laidley was former Kangaroo Daniel Motlop booting three goals against his old side.
Laidley spoke at length to his charges at three-quarter time, still giving his address as the Port Adelaide players resumed their positions.
The talk had minimal effect.
Port Adelaide was once again the dominant team in the final term – the only satisfying moment for North Melbourne coming when 300-gamer Shannon Grant snapped a goal.
North Melbourne 4.3 7.4 9.10 10.12 (72)
Port Adelaide 3.4 10.5 18.8 23.10 (148)
GOALS
North Melbourne: Hale 4, Grant 2, Jones, Campbell, Harding, Pratt
Port Adelaide: Rodan 5, D. Motlop 3, Gray 3, Thurstans 3, Cassisi 2, Logan, S. Burgoyne, Pearce, Lade, P. Burgoyne, Stewart, M.Motlop
BEST
North Melbourne: Hale, Petrie, Rawlings, Harvey
Port Adelaide: P. Burgoyne, Rodan, S. Burgoyne, K. Cornes, Brogan, Pearce, Logan
INJURIES
North Melbourne: Harding (knee), Wells (ankle)
Port Adelaide: Boak (ill) replaced in selected side by Lonie.
Reports: Nil
Umpires: Farmer, Schmitt, Mollison
Official crowd: 22,144 at MCG
