United's youngsters slipped to a disappointing defeat against Barnsley at Oakwell.
George Maris netted a hat-trick for the Tykes to settle the South Yorkshire derby in the hosts' favour.
The Blades started well and had the better of the early chances. Whiteman played in Smith who was denied by the Barnsley goalkeeper, before Charlesworth failed to hit the target after excellent interchange play involving Cockerline, Heh and Wright.
Maris got his first just on the half hour, latching on to a lay-off before sweeping the ball into the roof of the net from 25 yards.
Maris made it two with a well-taken individual effort on the stroke of half-time, evading the attentions of three defenders before netting with a left-footed finish.
The second-half followed a similar pattern to the first, but again Maris was the difference between the two sides. In the 61st minute he capitilised on a United mistake to lob Owen and ensure the matchball was his.
Blades coach Travis Binnion offered no excuses following the reversal, he remarked: "Barnsley thoroughly deserved their victory and they controlled the game for long periods. We are a young team and it could be a difficult end to the season, but we have to improve in order to be more competitive than we were on this occasion."
Blades: Owen, Charlesworth (Fixter 59), Ptak, Ishmail, Whiteman, Cheeseman, Heh, Partodikromo, Cockerline, Wright (Hallam 74), Smith (Kedman 59).