The first half had been tight, with Lee Miller threatening for United when his header from Lee Mair's cross nearly broke the deadlock.

But Deasley netted just after the hour mark with a shot which found the roof of the net, beating Derek Stille in the United goal.

The visitors thought they should have been awarded a penalty when Paul Dixon committed a suspected handball offence, and they also came close to an equaliser through Barry Robson late in the game when his shot was turned aside by Dundee goalkeeper Ludovic Roy.