In a topsy-turvy encounter at the Corbet Field, the visitors were eyeing up an upset when they took the lead just before the hour-mark thanks to a Gareth Holden cracker.
Back on his old stomping ground, the Manzur captain controlled Lorcan Smith’s hurried clearance with his first touch and, being urged to shoot while the Rec keeper was out of his goal, he rifled home from 40 yards to put his side 2-1 ahead.
However, their joy was short-lived as within two minutes Cusack hit back, reaching the ball just ahead of Kyle Carre to poke the ball past the outrushing Manzur keeper before composing himself to score.
The decisive moment came 12 minutes from the end when Zac Felbabel swung a corner to the far post where Ross Elliott headed it back across the face of goal and Cusack was on hand to stab home from close range to seal a 3-2 victory.
Earlier, Manzur had a problem to overcome before a whistle had even been blown with Leroi Riley dislocating a finger in the warm up and being replaced between the sticks by Carre.
Pete Robinson then gave Rec the lead on 24min. before Marlon Jardim equalised three minutes before half-time.
More in Thursday's Guernsey Press.
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