The Blades slipped to a heavy defeat against Huddersfield Town as defensive errors proved costly against the Terriers.
Shea Gordon scored a first-half equaliser after the visitors had fallen behind, but Town went on to net three without reply to seal the win.
United started well and had three good chances within the first 10 minutes. Fixter twice coming close before Smith's attempt was blocked by the home goalkeeper.
At the other end, in what was an open contest, Ramsdale had to save smartly twice in quick succession, but was helpless to stop the Blades falling behind in the 25th minute. United gifted possession away in their own penalty area and were duly punished from close range by SENIOR
The visitors were level within four minutes though GORDON linked nicely with Slew from a free-kick and the midfielder's shot went into the net off the post. Parity only remained for a further six minutes though, with KANE hammering in from a corner after Adebowale lost his man.
With half-time approaching a poor decision from Smith allowed Huddersfield to make it 3-1 from the penalty spot, with BOYLE taking full advantage of Smith's push, converting from 12 yards leaving United with a mountain to climb in the second-half.
United dominated for long periods after the restart with good chances falling the way of Gordon, Smith and Kelly, but with Town a constant threat on the break, the Blades were punished again in the 81st minute.
COOGANS converted from a cross on the right to put the game beyond the visitors, leaving Coach Travis Binnion to reflect on costly individual errors.
He said: "There are positives to take from the performance of what was a very young side, who showed a lot of character in the second-half.
"But we have to improve defensively and cut out the silly errors that are seeing us leak goals and making us chase games.
"It is going to be a tough end to the season, but we are giving the youngsters a chance as we look to speed up the development of our current U16s."
Blades: Ramsdale, Charlesworth, Semple, Adebowale, Kelly, Gordon, Brooks (Ramsey 66), Hinchliffe (Ishmail 66), Slew, Smith, Fixter (Lichfield 66).