It was debutant Corey Gameiro who kept the match scoreless in the early stages as Daniel McBreen headed at goal only for Gameiro to be in the right position to clear off the ball off the line.
The Mariners were the dominant force throughout the match but they continually let chances go begging as it looked like they would let the match slip away.
Josh Rose made an impressive run that ended up with him having his own chance at goal as he took a shot, only to be denied by good Vedran Janjetovic.
Matt Simon should have buried an opener moments later as he was found just five yards out from goal but could only send it wide.
Later on in the half Nick Fitzgerald had a golden opportunity as he was played clean through, beating the offside trap but he sent his effort over the bar.
In the latter stages Ranko Despotovic thought he'd given Sydney the lead as he rounded Liam Reddy but he was denied by the offside flag.
As the half nearly ended Reddy was vital as he spread himself to deny Ali Abbas' effort to keep the match scoreless at half-time.
Just after the break Sydney should have had the lead as Despotovic sent a ball on for Gamiero but snatched at the shot and couldn't find the goal.
In the 58th minute the Mariners finally hit the lead as Mile Sterjovski hit a powerful strike from just outside the box that deflected off of Matt Jurman's arm, leaving Janjetovic stranded and seeing the Mariners open the scoring.
New signing Milos Dimitrijevic came on after the goal in an attempt for Sydney FC to try and get a goal but it wasn't to be as the Mariners always seemed to be in control as they won the match.