St Kilda have won their way through to a preliminary final and condemned Geelong to the hard road in defence of their premiership, with a thrilling and controversial four-point win at the MCG on Friday night.
The Saints led the second qualifying final by as much as 33 points before falling over the line 12.11 (83) to 11.13 (79).
The titleholders appeared to have pulled off a famous win when, with one minute left on the clock, Cameron Mooney, one of the Cats' heroes on the night with three goals, laid a crunching tackle on James Gwilt.
The ball fell free to Geelong skipper Cameron Ling who snapped truly from 30 metres to put his team two points in front.
But field umpire Matt Stevic deemed that Mooney had pushed Gwilt in the back, the goal was disallowed and the Saints held on.
The Cats - who scored 1.7 in the final term - could or should have wrapped it up well before then.
Jimmy Bartel gathered a game-high 32 disposals for the Cats while Nick Dal Santo (29), Sam Fisher and Brendon Goddard were among the Saints' best.
Held to just four possessions in the first half, Joel Selwood put in an absolute shocker - one of the worst games of his decorated career with the Cats.
Opportunist snaps from Travis Varcoe and Mathew Stokes provided Geelong with all three of their opening-term goals.
When Varcoe dobbed his second - a looping effort from 30 that somehow eluded Sam Gilbert stationed on the goal line - the Cats led by 10 points.
At that stage the Saints had 1.5 on the board, a scoreline that included inexcusable misses from set shots inside 25, by Nick Riewoldt and Justin Koschitzke.
Before the quarter was out, however, both of St Kilda's key forwards had redeemed themselves.
The beneficiary of super passes from Brendon Goddard and Stephen Milne, Riewoldt, too quick and strong for Harry Taylor, goaled twice and 'Kosi' landed a long bomb from one of his five marks - two of them contested - for the term.
Late in the term, Lenny Hayes scored with a blow that was almost as telling when he floored Chapman with a perfect hip and shoulder that stung the feisty Cat and forced him to retire to the rooms for treatment to his left shoulder.
Milne was the star of the second term with an extraordinary burst of three goals in six minutes that extended the Saints' lead to 20 points.
Desperate to atone for his failure to take his chances in last year's grand final, Milne scored his first from a mark about 45 out and second from a free when held in a marking contest by Josh Hunt.
By this stage, the 'tip rat' was on a roll.
When he outmarked Hunt deep in the right pocket at the Punt Road end moments later, the percentage play would have been to stop and take the set shot.
But Milne - being Milne - played on, made the angle harder and still managed to dribble it through from tight against the boundary line.
Mooney kept the Cats in the contest with one early and one late, but a blast from distance by the imperious Goddard in time-on restored the Saints' advantage.
The forecast rain finally arrived at half-time compounding the task confronting the Cats.
Their assignment was made harder still when Clinton Jones scored the vital opening goal of the third term inside the first minute, an extraordinary effort on his non-preferred right foot from outside 50 that skidded through.
When that was followed by a long snap from Leigh Montagna that bounced through, the Saints' lead had blown out to a game-high 33 points.
The Cats were all but gone but fought their way back into it with five of the next six goals achieved with a combination of luck, a bit of magic, some kindness from the umpires and sheer force of will.
Mooney snared two of them - one of which appeared to be tapped through by Zac Dawson - and Steve Johnson got two - one from a very soft free for high contact - to narrow the gap to just 11 points at the final change.
The surging Cats conjured the first eight inside-50s of the final term for a net return of four behinds.
St Kilda's first attacking penetration was 12 minutes in coming, but they made it count.
Adam Schneider, a match-winner with four goals the last time these teams met, put it through the middle with a set shot from 35 totally against the run of play.
Chapman replied with the Cats' only major for the term moments later, but it was not enough.
GEELONG: 3.4, 5.6, 10.6, 11.13 (79)
ST KILDA: 4.7, 8.8, 11.11, 12.11 (83)
GOALS: Geelong: Mooney 3, Stokes 2, Johnson 2, Varcoe 2, Chapman, Byrnes
St Kilda: Milne 3, Riewoldt 3, Koschitzke, Gardiner, Gardiner, Jones, Montagna, Schneider
BEST: Geelong: Bartel, Chapman, Ling, Mooney, Ablett, Milburn
St Kilda: Goddard, Riewoldt, Fisher, Dal Santo, Jones, Milne, Hayes
INJURIES: Geelong: Nil
St Kilda: Nil
REPORTS: Nil
CHANGES: Tom Lonergan replaced by Shannon Byrnes in Geelong's selected side; Steven Baker and Jarryn Geary replaced by Robert Eddy and Sean Dempster in St Kilda's selected side
UMPIRES: Rosebury, Stevic, Ryan
CROWD: 63,608 at the MCG