The stunning result equalled the biggest winning margin in the history of Big Blue clashes, matching the Victory’s 5-0 win in 2005 in just the second match between the foundation clubs.

Fox Sports pundit Archie Thompson was wearing a Sydney FC jersey after the game after losing a bet but he didn’t have to work hard to let his feelings be known.

“That would have to be one of the darkest days in Melbourne Victory’s history. Tough to take,’’ Thompson said post-match.

The Sydney FC party started just three minutes in when Victory goalkeeper Lawrence Thomas appeared to completely misjudge a corner, dropping the ball as it rolled off Sydney FC’s Aaron Calver and into the net.

It was a dream start for Sydney FC and a nightmare for the Victory.

Former Socceroo Luke Wilkshire slammed Thomas’ first up miss at halftime.

“He needs to do better, he needs to command the box,” he said. “You can’t do that.”

The defending champions had no answer from that point with two late goals in the first half.

Alex Brosque scored a belter on the near-post before he put in an absolutely scorching strike which clipped the head of Leigh Broxham and beating Thomas for an own goal.

While Melbourne would have been hoping for a Liverpool-esque Champions League comeback, the hole just got deeper in the second half.

Fox Football commentator Mark Bosnich was savage on the Victory at halftime,

“Tactics are important but if you’re not first to the ball, if you’re not up for the battle, if you’re not thinking I’ve got to outdo the man I’m against, it all goes out the window,” he said.

The Sky Blues then marched into the grand final against the Perth Glory, doubling the lead with a humiliation of their great rivals before a late consolation goal.

Adam Le Fondre bagged a second half double to humiliate Kevin Muscat’s side and take revenge on the Victory for last years’ prelim shootout loss.

Milos Ninkovic’s late effort made it six, before Ola Toivonen’s last-minute header at least put Victory on the board.

In the 50th meeting of Australia’s biggest football clubs, only one came to play.

It sets up a mouth-watering clash between the Perth Glory, who edged Adelaide United in a shootout on Friday night, and Sydney FC for the title.

This was Sydney FC’s biggest finals win, Victory’s biggest loss, and a result no one saw coming.

Both sides had plenty to play for. Outside the grand final, both team captains had announced their retirements with Sydney’s Brosque and the Victory’s Carl Valeri set to end their careers.

As you would expect, Brosque was thrilled with the result.

“We just got everything right tonight, was just one of those games,” Brosque said. “Perth is a big challenge of course, they’ve been a great side all year. But tonight was a big challenge and we ended well.”

Valeri was gutted after the lacklustre performance by his side.

“There’s no nice way to put it and it kills me,” he said. “They should be very happy with their win. They outclassed us in every aspect and they taught us a big lesson here tonight.

“Unfortunately it’s (the) last lesson I will learn. We’ve worked hard all season and to go out all season like this is hard.”

The 2019 A-League Grand Final — and FA Cup Final — will be live and on demand on Kayo Sports for just $25 per month for two devices at once on Apple, Android and Telstra TV, for Apple and Google Android smartphones, on web browsers and via Google Chromecast Ultra devices. Click here for your free trial.

Fans also hit out the FFA and A-League after there were issues for the crowd with the gates not allowing fans to funnel into the stadium.

Some fans missed the start of the game as thousands of fans crowded to get into Netstrata Jubilee Stadium.

Fans were also disappointed with the 12,141 strong crowd.

— with AAP