Port Adelaide got down and dirty and proved they could thrive without star ruckman Paddy Ryder as they beat Sydney by 23 points at the SCG on Sunday.
The visitors absorbed plenty of first-half pressure and turned the heat on the Swans in the second to score a 14.10 (94) to 10.11(71) win.
Youngster Todd Marshall kicked three goals for Port and Ollie Wines racked up 35 possessions.
The visitors trailed by eight and 14 at the first two breaks, but slammed on seven goals to four in the third to carry a 15-point advantage into the final quarter.
Their lift in intensity pressured Sydney's normally composed defenders into some uncharacteristic errors and they weathered a brief Sydney comeback in the final quarter to secure their second SCG win in as many seasons.
Long-distance goals to Lance Franklin, who kicked a match-high four, and Dean Towers got Sydney back to within four points early in the final quarter, but Port kicked the last three majors.
Port's Charlie Dixon performed well when switched to the ruck in the second half.
Port coach Ken Hinkley attributed his team's stunning victory to their willingness to hang in there during a tough first half.
"As bad as the contest looked in the first half, the scoreboard was flattering and and that's what I pointed out to the boys at halftime," Hinkley said.
"We defended a lot of tough entries and our young backline did a great job to hang in and we just got a bit dirty we got down and got our hands on the ball.
"Charlie went into the ruck, Ollie turned into a beast, and (Steven) Motlop's game, there was just so many positives in the second half."
The first half was a dour struggle, with Sydney failing to make the most of 21 extra inside 50s, but by the end each team had notched 52 entries.
'We didn't take our chances in that first half and then we lost the territory battle," Swans coach John Longmire said.
"They were able to get momentum and score too easily."
Captain Travis Boak started Port's second-half surge by kicking two goals in a minute.
Marshall, who kicked four goals against Fremantle last week, also booted successive goals later in the third quarter, as Port took control.
Hinkley felt being without Ryder for all of 2016 meant Port had learnt how to compete better without their ruck linchpin, who he expected to be out for three to four more weeks.
He said having star forward Robbie Gray back from suspension proved the almost perfect swap for Ryder, as it was more of a ground level game.
Port's Chad Wingard had a sore hamstring, while Zak Jones was a late withdrawal from the Sydney side with a calf injury.