United's pre season ended in defeat at Elland Road today as goals by Morison and a late disputed Poleon effort saw the hosts win a competitive fixture 2-0.
United's visit to Elland Road for a first ever ever meeting with Leeds United was the final pre-season fixture for both clubs.
Amongst the crowd was former Tannadice full-back Andy Robertson who came hot-footed from his first training session with his new club, Hull City.
The Club's new away black with white trimmings was unveiled, though because of the colour clash, the players wore black, not white shorts, with the new white and black hooped socks.
For those looking for pointers for the make up of the side for the opening game of the season, manager Jackie McNamara made three changes from the team that had faced Hibs the previous Sunday.
Conor Townsend, signed on a season long loan from Hull City came in at left-back with Sean Dillon switching to the opposite full-back berth, occupied at Easter Road by Blair Spittal who was one of 11 substitutes.
Up front Chris Erskine and Brian Graham came in for Ryan Dow and Mario Bilate.
Unfortunately, United couldn't have made a worse start against the Championship side, conceding a goal after just three minutes.
Michael Tonge found space on the right before firing in a low cross which Steve Morison swept into the goal.
Within a minute, however, United came within inches of levelling when Callum Morris met a Nadir Çiftçi corner from the right to bullet a header fractionally over.
But it was the Yorkshire men who continued to make the running and after 12 minutes Rado Cierzniak beat away a sizzling shot from Rudy Austin.
Ten minutes later, Tommaso Bianchi crashed in a first time shot that struck the top bar but fortunately rebounded to safety.
Then on 27 minutes, John Rankin was the Tangerines' saviour, heading a Jason Pearce header from a corner off the line.
Just over half an hour had elapsed before United finally got in behind the Leeds defence.
Erskine played Stuart Armstrong in but his shot was straight at keeper Marco Silvestri.
One of the two substitutes made by Leeds after the break saw the introduction of former Tannadice favourite Noel Hunt.
Meanwhile, United emerged unchanged at the start of the second half but within two minutes had to make an enforced substitution after Dillon sustained a head knock after an accidental clash. Keith Watson took his place.
Soon there was a procession of substitutes with five replacements being made after 54 minutes - Armstrong, Çiftçi, Erskine, Graham and Rankin departing with Bilate, Dow, Mackay-Steven, Spittal and Telfer taking over.
Within five minutes, two of them set up United's best chance so far.
Mario Bilate played in Charlie Telfer whose shot came off the base of the near post.
Enjoying their best spell of the game, Blair Spittal then set up Bilate but he blazed his shot wide of the target from a good position.
Following a foul on Smith by Jarek Fojut, Noel Hunt fired a free-kick over the bar with ten minutes left.
And three minutes he later he set up a great chance, but for his former club!
His wayward pass sent Ryan Dow clear on goal, but his touch let him down and enabled Silvestri to narrow the angle and block his shot for a corner.
So it was harsh on the side's efforts to lose a second goal with four left, especially as Fojut appeared to be fouled by Smith when the ball ran lose to Dominic Poleon who rounded Rado to slot the ball into the empty net.
Team: Cierzniak, Dillon (Watson 48), Townsend, Fojut, Paton (S Smith 67), Çiftçi (Bilate 54) Rankin (Telfer 54), Graham (Spittal 54), Armstrong (Dow 54), Morris, Erskine (Mackay-Steven 54). Subs not used: McCallum, Connolly, Fraser, Petrie.
Referee: Andy Madeley.
Attendance: 10,115 (1,104 Arabs)