It was a matter of taking their chances when they came for the league leaders. Meanwhile, Olympic - who were backing up from an extra time FFA Cup defeat to Hellenic only 72 hours before - created enough of their own to claim something from the match, but failed to convert any in the final third.
Casuarina's first opportunity came from a free kick whipped into the penalty area by Gordon Pereira. It was placed perfectly on the head of Alexander Murrell who beat Olympic's defender to the ball. However, it was misdirected and propelled over the crossbar.
Causarina opened the scoring after 31 minutes. The black and white's caught Olympic stretched defensively. Skipper Imam Mukhlis hit a shot at Kane Mcadam who parried it back into the path of Ryan Newall. He slammed it with power into the back of the net from short range.
Olympic then had a string of close calls that came the way of Yuki Endo. The first was when he found the ball with no one taking responsibility for it in the box. Endo launched towards it and with a snap shot struck it towards the goal but it sailed way over the crossbar.
Olympic thought he had levelled 10 minutes after the teams returned from the interval. A corner whipped in from the right by Forkpah Ballah was neatly placed. Endo beat his man to get to the ball first, heading it with pace towards goal. Unfortunately for Michael Roditis' men, it hit the underside of the crossbar and was cleared by Casuarina.
Seven minutes later and again Endo went agonisingly close to restoring parity. He was fractionally late to a beautiful cross fed into the area by Kobi Jennings.
The missed chances hurt even more when Mark Casimiro doubled Casuarina's advantage after 74 minutes.
Luis Rodrigues' burst attracted Olympic Kane Mcadam off his line. The keeper slightly misjudged it, allowing Rodrigues to toe poke it past him. The ball slowly trickled towards the goal and Casimiro pounced to seal the match.