The Mariners were without both strikers Daniel McBreen and Tom Rogic with Adam Kwasnik and Adriano Pellegrino coming in while Mile Sterjovski was surprisingly chosen ahead of Bernie Ibini.
Perth Glory started well but both teams struggled for accuracy with neither keeper being troubled through the whole first half.
The Mariners best chance of the half came in the 17th minute when Pedj Bojic set up Michael McGlinchey only for the stand in skipper to miss the target.
Perth were not without their chances and their best came in the 36th minute when Steven McGarry crossed for Shane Smeltz who was wide open six yards out but shot high and wide, letting the Mariners off the hook.
The Mariners had one more chance in the half, in stoppage time as Josh Rose sent a cross for Kwasnik who was denied by former team mate Danny Vukovic’s save.
Right after the break McGlinchey was brought down earning Bas Van den Brink a yellow card only for Bojic to shoot well over the bar.
In the 68th minute the Mariners had their lead as Ibini controlled the ball and beat his defender before slamming home, although replays suggested that he controlled it with his hand.
Things went from bad to worse for Perth Glory in the 76th minute as Van den Brink was shown his second yellow card which left Perth a man down for the final 14 minutes.
That essentially killed Perth’s chances who looked dangerous until that point which handed the Mariners the advantage with Trent Sainsbury and Sterjovski both having opportunities to double their lead.