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The Mariners thought they had a got back into the game as O'Donovan raced onto a through ball behind the Phoenix defence and lifted the ball over Glen Moss, but his effort was ruled out for offside.
Liam Rose almost brought the home side level on the stroke of half time when he unleashed a powerful effort towards the top corner, but the keeper palmed the ball away from goal.
Central Coast got back into the game in the 76th minute when Anthony Caceres lifted the ball into the box from a corner and O'Donovan rose highest in the box to guide a headed effort past Moss.
The Mariners pushed for a winner late on and substitute Josh Bingham almost got the goal, only to be denied by a fine save from Moss, which was enough to earn the visitors a point.
The result leaves Central Coast in eighth place in the table, while the Phoenix are one place above them in seventh.