Curtin�s only goal came from the boot of Dilip Thapa, who fired home from distance in the first half.
The home side dominated for large periods of the game but could not put its chances away as Oliver Rigler and his Balga defence stood firm for the visitors.
Curtin started the brighter of the two sides in wet conditions and hit the lead after 10 minutes when Carlo Chiellini picked out Thapa in space and his searing drive nestled in Rigler�s bottom corner.
Chiellini then had the next two chances of the match but he fired over on both occasions. Khaled Salhah also had a chance to score for Curtin but Rigler made a fine save down to his left.
Balga then drew level through George Duku as the striker pounced on a slip from Curtin �keeper Mackenzie Ferguson to score in an empty net.
Jonathan McGahern then put the visitors in front with a fine strike from the edge of the box against the run of play.
Controversy was to follow as Duku was shown a yellow card by the referee when others believed he should have been sent from the field.
Curtin continued to search for an equaliser, finding promise from both Kristian Beven and Kye Middleton down the flanks, but the home side was wasteful in the final third.
With 15 minutes to play, Eddie Tikoft was shown a second yellow card, leaving them with an evertougher task.
They continued to dominate possession, however, but Balga held on to take the three points.