Terry Antonis went from zero to hero as Melbourne Victory ended Sydney FC's A-League defence and booked a place in the Grand Final with a stunning 3-2 win after extra time at Allianz Stadium.

Former Sydney midfielder Antonis agonisingly put through his own goal with 12 seconds of the allotted five minutes of second-half stoppage time left, but he came to Victory's rescue in a dramatic change of fortunes with a solo effort in the 117th minute.

The 24-year-old managed to avoid a second yellow card for celebrating with the crowd and appeared to be in tears after getting the winner, while Sydney coaches Jean-Paul de Marigny and Dean Anastasiadis were dismissed following a video review of an on-pitch scuffle with David Carney in the aftermath.

Victory gained a measure of revenge for losing last year's showpiece to Sydney and now travel to Newcastle Jets for a Grand Final that pits former Melbourne manager Ernie Merrick, who oversaw their first two A-League title triumphs in 2007 and 2009, against Kevin Muscat, his captain during that period, next weekend.

The result brought about a bitter end to Graham Arnold's Sydney tenure, with the 54-year-old leaving to take charge of Australia after the World Cup.

Sydney became the first team to defend the Premiers' Plate this season and appeared on track for a return to the Grand Final when Adrian Mierzejewski's free-kick deflected off Stefan Nigro and got the better of Lawrence Thomas.

Kostas Barbarouses, who hit the post earlier in the half, equalised after the half-hour mark thanks to a nick off Jordy Buijs, and James Troisi finished off a fine pass from Besart Berisha to give Victory the lead 72 seconds after the restart.

Ben Warland hooked a volley against the crossbar and narrowly missed the target with a header as the hosts pushed for to restore parity in stoppage time, and it finally came when Antonis shinned Mierzejewski's cross into the roof of his own net.

With legs tiring towards the end of extra time, Antonis atoned for his error by getting away from two defenders on the right and beating Andrew Redmayne, sparking scenes of delirium among the visiting fans in an incredible finale.