With skipper Joel Selwood at his brilliant best, the Cats put their foot down after half-time en route to an eye-catching 19.10 (124) to 16.7 (103) win over the reigning premiers.
Just as the Swans had done to North Melbourne last week, it was a third-quarter blitz that gave Geelong its match-winning lead in front of 31,060 fans.
With Tom Hawkins dominant up front and Selwood and Steve Johnson pulling the strings, seven goals to one in the third term gave the Cats a 31-point lead at the last change.
Selwood filled the stat line with 30 possessions, nine tackles, seven clearances, seven inside 50s and a goal, while Hawkins and Steve Motlop kicked three goals each for Geelong.
It was an uncharacteristically flat display from the Swans, who lacked their usual defensive intensity and were guilty of some poor discipline.
Dan Hannebery (29 disposals, two goals) was the home side's best despite battling a leg problem and Nick Malceski battled hard, but a number of their stars were well beaten.
Josh Kennedy had just 16 touches to three quarter-time and 23 for the game, with fellow midfielders Ryan O'Keefe, Kieren Jack and Luke Parker also unable to have their usual influence.
They also have some injury concerns, with versatile big man Lewis Roberts-Thomson substituted in the second quarter with an apparent right knee injury.
The game started at a frenetic pace, featuring some of the most breathtaking football sighted anywhere in the country this season.
Two sides that usually relish a fierce, contested style found acres of space on the confines of SCG, leading to a stunning 15-goal first quarter.
Jude Bolton's second goal late in the term gave the home side a five-point quarter-time edge.
"I think I picked the wrong style of game," David Parkin said on ABC Radio after his prediction of a hard-fought, lock-down evening.
"What happened to Swans footy? This is amazing to watch," added former Swans defender Craig Bolton.
It was a pace that was never likely to be maintained, and the contest duly slowed down in the second quarter.
With both teams lifting their intensity, no doubt after some none-too-subtle reminders by the respective coaches, it was suddenly a very different style of game.
Two early goals to the Swans gave them a 19-point lead as they tried to break the game open, but the Cats were able to answer, kicking two goals of their own as the five-point margin remained at half-time.
From that point it was all Geelong as they inflicted the first defeat of the season on the Swans.
James Dampney is a reporter for AFL.com.au. Follow him on Twitter: @AFL_JD
GEELONG 7.2 9.4 16.7 19.10 (124)
SYDNEY SWANS 8.1 10.3 11.3 16.7 (103)
GOALS
Geelong: Motlop 3, Hawkins 3, Taylor 2, Chapman 2, Stokes 2, Horlin-Smith, Podsiadly, Smedts, Johnson, Selwood, T. Hunt, Christensen
Sydney Swans: McVeigh 3, Goodes 2, Bolton 2, Hannebery 2, Malceski 2, Reid, Roberts-Thomson, Pyke, McGlynn, Kennedy
BEST
Geelong: Selwood, Taylor, Hawkins, Motlop, Corey, T. Hunt
Sydney Swans: Hannebery, Bolton, Pyke, O'Keefe, Malceski, Goodes
INJURIES
Geelong: Nil
Sydney Swans: Roberts-Thomson (right knee)
SUBSTITUTES
Geelong: Billie Smedts replaced by Josh Caddy at three-quarter time
Sydney Swans: Lewis Roberts-Thomson (right knee) replaced by Mitch Morton in the second quarter
Reports: Nil
Umpires: Donlon, Stevic, Stewart
Official crowd: 31,060 at the SCG
