With three wins from as many starts and having already built a four-point lead at the top of the standings, Sydney were home favourites against a side which had recorded two draws in their two matches to date.

The visitors, though, lined up with four over age players in Brad Porter, Lachlan Cahill, Matthew Crowell and former Socceroo Ahmad Elrich. The home side conversely fielded Adam Casey as their only senior squad member.

Sydney continued their early season momentum with a bright start that produced a goal after just 90 seconds from Joel Chianese, the midfielder firing home with a clinical finish from the edge of the penalty area following good lead-up on the right flank from Hussein Akil.

With large chunks of the early exchanges played out in the midfield Sydney opened up the Mariners defence twice in quick succession with firstly Akil, and then Casey, unable to take advantage of some good openings.

The Mariners came to the fore in the latter stages of the half and were duly rewarded as Cahill unleashed a stunning strike into the top corner of the goal from 20 metres.

The Mariners commenced the second stanza in a similar vein to Sydney's opening to the match with half-time substitute Mitchell Mallia scoring with his first touch two minutes after the interval. Porter's cross was punched only half clear by Blues goalkeeper Nenad Vekic, with Mallia drilling the loose ball into the roof of the net from near the penalty spot.

Four minutes later the Mariners sensationally doubled their lead. Captain Panni Nikas ghosted in behind a static Sydney defence to score with an easy header from an Elrich cross, the Mariners captain continuing a marvellous scoring streak at same venue with the NSW Premier League champions Sutherland Sharks.

Buoyed by the goals the Mariners continued their momentum with a swerving free-kick from Porter causing difficulties for Vekic.

Increasing rain and a host of substitutions made for a somewhat disjointed second half with the visitors always looking capable of maintaining their advantage.

Sydney's afternoon perhaps summed up in the dying minutes as Kerem Bulut struck the crossbar when clear through on goal, and then Iain Ramsey having a goal disallowed having been ruled marginally offside.