The Tangerines dominated possession but could not convert any chances and in the end ran out of ideas whereas the visitors had two chances and converted both of them.
From the outset United played as if they were in holiday mood with slack passing and general lethargy across the park. It came as no surprise when they were punished in the 12th minute as some woeful defending gifted the opener to Kenny Deuchar.
Under no apparent danger, Stuart Duff elected to lob the ball back to his keeper Euan McLean. However, the youngster was slow to clear allowing Deuchar to tackle him and tap the ball into an empty net for his first goal since returning to the club.
Despite this setback, the hosts continued to toil until they grabbed an equaliser in the 29th minute courtesy of Noel Hunt.
A fine three-man move involving Garry Kenneth and Sean Dillon ended with the right-back curling in a cross for the unmarked striker to nod the ball in from six yards.
The goal seemed to inject some life into the Tannadice terraces and United came very close to taking the lead through Hunt and David Robertson before they gave their opponents another gift-wrapped goal in the 42nd minute.
A deep cross was missed by Duff allowing Deuchar to head the ball down. With the keeper all at sea, it was an easy tap-in at the far post for Nicky Deverdics.
Ten minutes later, as United pressed, Hunt missed from only three yards and Tony Caig touched a Barry Robson cross over the bar.
It became very much one-way traffic and United should have equalised in the 77th minute when Robson dribbled past three players but, with the goal at his mercy skewed his shot wide. It was a finish which summed up United's day.