United were no match for Qatari side Aspire who posted a 5-1 victory in the Milk Cup final in Ballymena.
The young Reds had no answer to formidable opponents, who trounced Desportivo Brasil 6-1 in the semi-finals, and were put out of sight by a Ibrahima Drame hat-trick within 25 minutes.
The giant No9 picked up the tournament's Golden Boot after heading in the opener when Franck Cedric Tchoutou raced past makeshift full-back Gyliano van Velzen to cross to the near post.
More good approach work by Cedric allowed Drame to display another clinical finish and, soon afterwards, his unstoppable header flew past Joe Coll from Innocent Shoja's cross. United were shell-shocked and took 44 minutes to register their first shot through Mats Daehli.
But, to their credit, Paul McGuinness' side improved after the interval to show the kind of flowing football that was their hallmark in the group stages. Substitute James Wilson was thwarted by Dungong Francois following a fine move but Drame created more havoc at the other end to set up another goal on the break for Pape Babacar and further deflate the boys from Manchester.
On the hour mark, Jack Barmby pulled one back when reacting quickly to a Tyler Blackett free-kick and seeing his shot squirt under Francois and over the line before Wilson could make sure.
Oumarou Kaina added a fifth after a bold run by substitute Samuel Darko and the woodwork came to Coll's rescue before Wilson and the outstanding Drame traded late chances as it finished 5-1.
It will be an important lesson learned for McGuinness' charges and helpful in their development and nothing should be taken away from their excellent progression to the final in Northern Ireland.
United: Coll; Hendrie, McCullough, Blackett, van Velzen, Pearson, Rudge Rothwell, Barmby, Lawrence (Wilson), Daehli.