Port won by 76 points, 23.10 (148) to 10.12 (72), which means if any of Adelaide, St Kilda or the Sydney Swans wins later in round 22, North will face a sudden-death final next weekend.
The Kangaroos looked comfortable early, and had a three-goal lead in the first quarter before the Power took control. The game was all over at three-quarter time, and North players spent the last quarter making sure they incurred no injuries with a finals' campaign looming.
After kicking the first three goals of the match, North was outscored by seven goals to 23, and goes into September action with a chastening loss behind it.
Peter Burgoyne had the ball on a string with 45 disposals, while Kane Cornes smothered North playmaker Daniel Wells and also won plenty of the footy, finishing with 30 possessions. David Rodan was outstanding with five goals.
Few North players had any impact, although Brent Harvey was typically lively until he spent most of the last quarter marooned in the forward line, and David Hale again provided a strong marking option in attack and snared four goals.
Port blew the game away in the third term with eight goals to North's two, but the Kangaroos' grip on the double chance was looking shaky as early as half time when Port held an 18-point lead after a seven-goal quarter.
Hale, who played a virtual lone hand in attack for the Roos, kicked a goal on resumption after the main break to cut the margin to 12 points, but from then on the Power were supreme against a horribly off-the-boil North.
Rodan, who was dangerous around the packs all afternoon, goaled twice to restore and then extend Port's half-time lead, and a procession followed, with majors to Daniel Motlop (twice), Toby Thurstans (twice), Brendon Lade and Robbie Grey stretching the margin to a shade short of 10 goals.
Hale, in red-hot form after eight goals against Geelong last week, kicked his fourth for North late in the quarter, but Drew Petrie summed up the Kangaroos' day when he hit the post with a set shot after the three-quarter time siren.
Port's supremacy in midfield was translated onto the scoreboard after the Roos had broken away to a 19-point lead half-way through the first quarter.
Brent Harvey was brilliant early for finals-bound North, but playmaker Daniel Wells was totally smothered by the Power's key stopper Kane Cornes.
North was missing the run from half back of Leigh Harding, who left the field in the opening term with what appeared to be a serious injury to the left knee he had reconstructed in 2006.
Gray fell across Harding's knee when the North man tackled him late in the first quarter. To add insult to injury, Gray won a free kick and goaled.
Since being shifted to defence, Harding has enjoyed the best season of his career, playing every game bar one after he was sidelined all last year.
Travis Boak was a late withdrawal for Port Adelaide, replaced in the selected side by Nathan Lonie.
PORT ADELAIDE 3.4 10.5 18.8 23.10 (148)
NORTH MELBOURNE 4.3 7.4 9.10 10.12 (72)
GOALS
Port Adelaide: Rodan 5, D. Motlop 3, Gray 3, Thurstans 3, Cassisi 2, Logan, S. Burgoyne, Pearce, Lade, P. Burgoyne, Stewart, M.Motlop. North Melbourne: Hale 4, Grant 2, Jones, Campbell, Harding, Pratt
BEST
Port Adelaide: P. Burgoyne, Rodan, S. Burgoyne, K. Cornes, Brogan, Pearce, Logan. North Melbourne: Hale, Petrie, Rawlings, Harvey
INJURIES
Port Adelaide: Boak (ill) replaced in selected side by Lonie. North Melbourne: Harding (knee), Wells (ankle)
Reports: Nil
Umpires: Farmer, Schmitt, Mollison
Official crowd: 22,144 at MCG
The views in this article are those of the author and not necessarily those of the clubs or the AFL.
