Soon after, McGowan turned provider, twisting and turning to pull the ball across the goal from the byline, and Mooy was perfectly placed to turn home.
The Buddies made two changes for the match, David van Zanten and Hugh Murray coming in for Aaron Mooy and Marc McAusland who both started on the bench.
And the hosts broke the deadlock just before the half-hour mark when McAusland rose to meet Mooy's corner from the right and power a header past Mark Howard.