PORT Adelaide conquered Geelong by 40 points to inflict the Cats' first loss of the season and stamp itself as a genuine flag fancy.
The Power prevailed 16.11 (107) to 9.13 (67) in Sunday's Adelaide Oval twilight fixture to join Hawthorn and the Cats at the top of the table.
The trio all have five wins and a loss after Port dismantled the Cats in grand style before a raucous home crowd of 47,007 spectators.
The Power were inspired by the ball-winning feats of captain Travis Boak (32 disposals, two goals), vice-captain Brad Ebert (28 possessions) and Kane Cornes (33 touches), while forward Chad Wingard kicked three goals.
Port's livewire forward Robbie Gray capped his outstanding game with two goals, a return matched by teammates Hamish Hartlett, Matt White and ruckman Matthew Lobbe.
Power coach Ken Hinkley said that although the win was a good one for the club, he wouldn't get too excited by the result.
"It was a really strong performance against great quality opposition who are a fantastic team … we had to be at our absolute best," Hinkley said.
"We [went] to West Coast last week and played, we've had three games on the road, we've had some big build-ups and we've been able to handle the pressure most of the time.
"We've been able to handle the pressure but it's hard – it's round six, it still doesn't say too much about the rest of the season."
The Cats were well-served by Matthew Stokes (28 disposals), Steve Johnson (25 touches) and Mitch Duncan (27 possessions) but butchered a host of scoring chances with errant goalkicking.
Key forward Tom Hawkins slotted three goals from limited opportunities and JoshWalker booted two but the Cats paid the price for wasteful goalkicking, particularly in the second quarter.
In a freewheeling game, Geelong held a two-point advantage after both sides kicked four goals in the opening quarter.
Both teams then had five scoring shots in the second term: the Power logged 4.1 while Geelong returned just five points.
Geelong's inefficiency helped Port create a three-goal break at half-time - a margin the rampant hosts doubled in the initial six minutes of the third term when the influential Gray slotted his second.
Cats coach Chris Scott described the inaccuracy as "demoralising".
"I actually thought we were OK, I thought the scoreboard was a fair reflection of the evenness of the game," Scott said.
"We weren't able to put pressure on them by taking our opportunities and they certainly took theirs.
"It tends to be quite demoralising, irrespective of the character of your people when you blow chances at one end and then get opened up at the other.
"We had a lot of very good players who were down tonight."
The Cats briefly rallied but could only get within four goals before Port kicked away again, taking a defining 38-point buffer into the last quarter.
Port's reigning club champion Wingard then capped a stunning Port victory with two quick goals in the last quarter.