Kosta Petratos' last-minute goal has handed Newcastle Jets a last-gasp 2-1 win to not only spoil Sydney FC's Premiership party but keep their faint finals hopes alive.
Needing only a point to clinch the Premiers' Plate, the Sky Blues had one hand on the silverware when Anthony Caceres had them leading 1-0 at the break.
But a stunning goal from Nick Fitzgerald just after half-time followed by Petratos' maiden Hyundai A-League goal in the final minute shocked the hosts and handed the Jets a memorable victory.
The result was just Newcastle's third win over Sydney FC in their last 21 meetings, while it has kept them in the race for the Finals Series.
Carl Robinson's side, who were excellent value for their win, sit just three points outside the top six and have three matches still to play.
It was just Sydney FC's third defeat of the campaign and means they will need to wait a little while longer to secure what would be their third Premiership in the last four seasons.
The Sky Blues will clinch top spot if they avoid defeat in their next match against Melbourne City on August 1, or they could do it as early as Wednesday night if Wellington Phoenix fails to beat Perth Glory.
Slick move puts Sydney in front
After an even opening 20 minutes, the Sky Blues started to find their groove and took the lead with a fine team move.
Rhyan Grant and Alexander Baumjohann combined brilliantly down the right, with the latter bursting past Angus Thurgate to get to the byline.
And the German showed great composure to pick the perfect pass into the middle where a combination of Caceres and Jets defender Matt Millar bundled the ball into the net.
Redmayne comes up big to deny Jets
Grant picked up an injury and was replaced by Harry van der Saag just after the half-hour mark and the Sydney FC youngster was soon in the thick of the action.
Van der Saag was disposed of the ball deep in his half by Steven Ugarkovic, who immediately released Roy O'Donovan with an inch-perfect pass.
The Irishman – playing his 100th game in the Hyundai A-League – looked set to equalise only to be denied by a superb save by the feet of Redmayne.
Woodwork denies O'Donovan this time
It was the Jets who made the stronger start to the second half and it was only the width of the post that denied them a deserved equaliser.
Some sloppy play from Barbarouses on the edge of his box allowed Nikolai Topor-Stanley to pinch the ball and feed O'Donovan, who was again one-on-one with the Sydney shot-stopper.
The Jets striker's shot this time beat Redmayne but rattled the post before the Sky Blues were able to scramble the ball away.
Fitzgerald with a spectacular equaliser
Newcastle's dominance was soon rewarded though and they responded just before the hour mark through a spectacular finish from Fitzgerald.
Matt Millar dinked an inviting cross to the far post where Fitzgerald was in space, with the Jets attacker producing an acrobatic scissor kick to fire past Redmayne.
It was just what the visitors deserved and prompted Sky Blues boss Steve Corica into a triple substitution soon after.
Petratos wins it at the death
Kosta Petratos chose the perfect time to score his first Hyundai A-League goal with a smart finish in the final minute.
Picking up the ball with his back to goal on the edge of the box, Petratos turned his defender before firing a shot past a stranded Redmayne.