St Kilda have stunned Collingwood by 15 points, relegating the Magpies to a 0-3 hole in their AFL premiership defence.
Saints forward Jack Higgins kicked a freakish but controversial goal during the final term to blunt Collingwood's late rally in the 14.10 (94) to 12.7 (79) win on Thursday night at the MCG.
This was the Saints' fourth annual "Spud's Game", honouring St Kilda great Danny Frawley, and the first of them they have won.
St Kilda's opening win of the season came at a cost, with Mason Wood taken to hospital after a heavy collision with teammate Zaine Cordy in a first-quarter marking contest.
Coach Ross Lyon later confirmed Wood has a broken collarbone, as well as concussion.
Livewire recruit Liam Henry also left the field in the final quarter after he had been one of the Saints' best players. Lyon is hopeful it is only a severely cramped hamstring.
Lyon said they learned their lessons after last week's loss to Geelong, when they pressed the Cats but lacked method.
"We buttoned down, really got our press game going, and we really got to work ... creating a lot of turnovers," he said.
"If you're a reigning premier, you've got clear signatures that we need to deal with - the competition has maybe taken a while, but we're seeing all those signatures.
"Often it's hard to stop, but tonight we did a pretty good job of that."
The Saints kicked the first two goals of the last term to take a game-high lead of 33 points.
But as has become their custom, Collingwood fought back with three goals, and with Henry out of the game suddenly St Kilda were vulnerable.
Then Higgins was on the boundary line in a forward pocket when he snapped his fourth, a goal-of-the-year contender, that steadied the Saints.
But there will be plenty of debate about whether Higgins was out of bounds when he took his miracle shot.
It was reminiscent of one of the darkest moments in Collingwood history, when Carlton's Wayne Harmes knocked the ball back into play from about the same spot at a critical moment in the Blues' 1979 grand final win.
There remains considerable debate about whether that ball was out of bounds as well.
Magpie fans will point with frustration to Thursday night's free-kick count, 30-15 in the Saints' favour.
Saints half-back Nasiah Wanganeen-Milera starred with 32 possessions, while ruckman Rowan Marshall also was mighty.
Collingwood again looked well off their best, and Brisbane coach Chris Fagan was an interested spectator at the MCG ahead of next Thursday night's grand final rematch at the Gabba.
"Everybody out there can see it, there's just fundamental stuff that we're doing really poorly," said Magpies coach Craig McRae.
"Things a little bit uncharacteristic to our game - also from experienced players.
"It's just little things that mean big things.
"At the end of the day, if you have too much cheese on your lasagne, it doesn't matter - it won't affect the result.
"The cheese on the lasagne, that doesn't matter - you have to get busy and do the things right. The fundamentals of the game are really important and that's where we'll put our energy."
Premiership stars such as Steele Sidebottom and captain Darcy Moore were below-par against the Saints.
Play was held up for several minutes in the first term as Wood was stretchered off.
That blunted Collingwood's early momentum and the Saints rallied to lead at quarter time.
Collingwood hit back to lead by eight points at the main break, before the Saints kicked eight goals to five in the second half for a hard-fought win.
Josh Daicos shone for the Magpies with 29 possessions on a wing.
