United's U18s ended the season on a five-match unbeaten run, following a dramatic late victory at Barnsley on Satuday.
A last-gasp strike from U15s striker Ryan Viggers proved to be the winner at the Oakwell Academy, after a first-half penalty from Reon Potts.
Barnsley were the first to threaten with an effort being saved brilliantly by Dewhurst as he pushed past the post on the stretch.
On 17 minutes though, the game turned decisively in United's favour as the Barnsley goalkeeper was sent off for bringing down the advancing POTTS in the area and the Blades youngsters confidently scored from the resulting penalty to put the visitors ahead.
The second-half saw United dominant for long periods, with Neal firing just wide of the post after patient a build up.
With 20 minutes remaining the points were almost secured as Capello and Boyes linked up well on the left, eventually finding Kelly who's effort bounced off the post.
However Barnsley looked to have snatched an unlikely point as a long ball over the top caught out the United defence and the forward slotted home with 88 minutes on the clock.
But deep into stoppage time, United rolled the dice one final time, Capello worked his way to the byline and fired across goal for VIGGERS to fire in to spark celebrations on and off the field, as United ended the campaign on a real high.
Blades: Dewhurst, Williams, Boyes, Neal, Weaver, Gordon, J. Kelly, Broadbent, Potts (Stainrod 78), Ompreon (Viggers 65). Capello.
Unused: England, Clarke.