It was the match Sydney FC were never supposed to lose.
After another record-breaking regular season, the Sky Blues won the minor premiership by 14 points over Newcastle Jets.
They finished an extraordinary 23 points ahead of semi-final opponent Melbourne Victory - who had spluttered to eight fewer wins than Graham Arnold's side in the home-and-away campaign.
The Sky Blues had won seven matches in a row against their Big Blue rivals dating back more than two years to February 2016.
In front of a parochial crowd of nearly 18,000 at Allianz Stadium, Sydney FC took the lead against Victory on 24 minutes after an unfortunate own goal by Stefan Nigro.
But they could only hold their advantage for seven minutes as Kosta Barbarouses was allowed too much space in the box before firing a wickedly deflected strike into the back of the net.
Almost immediately after the half-time restart, Victory took a shock lead when James Troisi ghosted in at the back post to tap into the empty net after Besart Berisha's slide pass.
The Sky Blues threw absolutely everything at the visitors from this point onwards, with Victory goalkeeper Lawrence Thomas making a number of crucial blocks.
Fringe Sydney FC defender Ben Warland hit the crossbar in the 92nd minute with a looped volley before going agonisingly close with a header barely 60 seconds later.
But the sheer weight of chances and pressure eventually told as the premiers sent the contest into extra time after Terry Antonis inexplicably put the ball into his own net from close range with 15 seconds of normal time to play.
Victory coach Kevin Muscat had hedged his bets on winning the match in 90, withdrawing perhaps the team's best three players - Leroy George, Berisha and Troisi - for fresher legs in the latter stages of the match.
After the devastation of failing to win when the match was in their grasp, how was Victory going to create chances in extra time with their match-winners off the pitch, coupled with the momentum Sydney FC had from keeping their season alive?
With fringe attackers Kenny Athiu and Christian Theoharous leading the line alongside a tiring Barbarouses, Victory barely looked like getting the ball into their own half let alone creating a chance.
And it took one of the most extraordinary moments in A-League history to get them into the grand final.
The villain Antonis, who had tears in his eyes after giving his former side a lifeline, picked up the ball in his own half, and despite not being blessed by pace, fought his way through multiple challenges to score the winning goal via a deflection.
What if Milos Ninkovic had have connected with his sliding tackle? What if Brandon O'Neill dragged Antonis down by the shirt to make a professional foul at the expense of a yellow card?
We will never know what would have happened if the match went to penalties but Victory would have remembered the results of the shootouts against the Sky Blues in the 2010 and 2017 grand finals.
In the present day, the two teams forming the A-League's greatest rivalry will square off once again in Sydney on Sunday for a place in the A-League's grand final against either Perth or Adelaide.
There will be superstars all over the pitch - with Sydney led by Adam Le Fondre, Milos Ninkovic and Siem de Jong, while Victory will feature Keisuke Honda, Ola Toivonen and Kosta Barbarouses.
Will the Sky Blues be haunted by last season's result at the same stage? Will Victory's incredibly shaky defence hold up in the heat of the battle?
The Big Blue blockbuster is nearly upon us. Bring it on.