For the second successive game, Stevie Campbell's side fired blanks, and that, combined with a momentary defensive lapse saw them slip to defeat on the Astroturf at Stenhousemuir.
That aberration came fifteen minutes from time when Jamie Murphy was allowed to cut in from the right and he angled a shot across keeper John Gibson into the far corner from twelve-yards.
This was hard on the Tannadice youngsters because in a game where defences were very much on top, they definitely had the better of it in terms of possession, but crucially lacked any real cutting edge.
After an uneventful opening forty-minutes, the first half finished with a flurry of activity around the Motherwell goal. First Michael O'Byrne headed over and then Scott Mathieson had an effort blocked with Ryan McCord firing just past.
Into the second half and United continued to have the better of what few chances there were. Certainly, Ryan McCord should have done better than fire over twelve minutes after the re-start and with twenty minutes left Fraser Milligan was close with a drive that drifted just past.
Two minutes from time, Johnny Russell almost equalised, but his header went the wrong side of the post. Yet it took a fine save from John Gibson right at the death to prevent Jamie Murphy bagging a brace that would have given his side a flattering second.
Team (4-5-1): Gibson, Milligan, McMechan, O'Byrne, Pope, Jeffrey (Feeney 80), Mathieson, Andreoni, McCord. Paterson, J Russell. Subs not used : McGrath, Allan, Colgan.