He has the distinction of having scored the last goal of the now defunct NSL when he scored a golden goal winner in the 2004 Grand Final for Perth Glory against Parramatta Power.
This was to remain the high-point of Mrdja's season as he was injured from the final of the Pre-Season Challenge Cup. Mrdja scored his first goal for the Mariners on 19 November 2006 against the New Zealand Knights, after almost two years on the sidelines. It was his first in Australia since scoring the winner in the 2004 NSL Grand Final.