In front on 3485 fans at nib Stadium, Sydney made a blistering start to the contest as Robert Stambolziev was brought down in the area just two minutes in.
Shane Smeltz stepped up to convert the penalty and give the visitor a 1-0 lead.
Sydney continued to dominate but was unable to add to its advantage, even missing a penalty 10 minutes into the second half.
Graham Arnold's side finally made its pressure count 15 minutes from time as substitute Max Burgess made it 2-0.
In the Northern Territory, Darwin Olympic made a promising start to its meeting with FFA Cup holder Adelaide United.
But it fell behind on 17 minutes after Osama Malik won a penalty and Marcelo Carrusca coolly converted.
The Reds lead was short lived as Darwin hit back almost immediately through Michael Tsounias, much to the delight of the passionate home support.
Just before the break, Adelaide regained control of the contest as a double from Jimmy Jeggo in the space of a few minutes had the Reds 3-1 up at half-time.
A superb strike from Sergio Cirio in the closing stages, made absolutely sure of the result for Adelaide.
There was still time however for Reds debutant Eli Babalj to score his first goal for the club.
Pablo Sanchez rounded out a highly impressive performance for Adelaide with a sixth goal late on.
Fellow South Australian side Croydon Kings was unable to mimic the Reds performance, despite a strong finish in its tie with Queensland Lions.
Lions held on to their two-goal half-time lead to claim a 2-1 win on the road.
In Sydney, Rockdale City Suns got the better of Perth SC with a comfortable 3-1 victory.
