However it was the visitors who began strongly and inside two minutes a cross from the right was flicked on by Paul di Giacomo to Tommy COYNE who made no mistake.
Soon after, Steve Lovell found himself through on goal but keeper Cameron Bell produced a good save and the keeper was in action again throughout the half to deny Lovell, Andrew Considine and John Stewart.
In the 62nd minute Aberdeen levelled when a through ball from Ashley McInnes was helped on by Stewart to Kyle MACAULAY, who turned before rifling the ball past Bell.
The decider came in the 81st minute when substitute Andy Bagshaw's cross was met at the far post by MUIRHEAD who fired a sweet left foot volley into the net with Bell helpless.