Trialist Jordan Robertson scored with the last kick of the game as the Blades recorded an impressive win over Leeds United at Shirecliffe on Tuesday afternoon.
Given the first team's clash against Crawley Town on Tuesday evening, David Unsworth took charge of the team that was made up solely of his U18 players, with the exception of trialists Hilliard Carrillo and the aforementioned Robertson.
The young Blades more than held their own against the visitors, who themselves included, Dominic Poleon, Ryan Hall, Rodolph Austin and Habib Habibou in their starting line-up.
The game started with both teams having a sight of goal. McDonagh curled wide for the hosts, whilst at the other end Willis saved with his legs to deny former United loanee Poleon.
The rest of the first-half was a quiet affair with neither side creating too much in the way of goalscoring opportunities.
After the half-time break, Poleon burst into the box, only to see his shot hit the post. Moments later, the Blades should have been in front, but Grimes saved smartly to his left to deny Smith, at the other end Willis came to United's rescue with a fantastic double save from Habibou.
After a long stoppage following a serious injury to Leeds left-back Snodin, Dimaio for the Blades and Hall for the visitors both had chances to put their respective team ahead.
As the 90th minute approached, the home side thought they should have been awarded a penalty after two defenders converged to halt Smith's progress, but the referee waved away the subsequent appeals.
Deep into injury-time, though, United forced the breakthrough with the final kick of the game, ROBERTSON coolly slotted the ball past Grimes from inside the penalty area.
Speaking after the game, Unsworth was delighted with the application and desire of the youngsters.
He said: "It was a fully deserved win and we are so proud of the lads, they were resolute, determined, committed and most of very disciplined. We set them up slightly differently to an Academy game, but they didn't deviate away from what I told them.
"I spoke to Morgs and told him the lads and won him all three points, he was understandably delighted and I am so proud of the boys.
"It is a great win and a tremendous confidence boost for everyone, Leeds fielded a much more experienced team, but our players couldn't have given us anymore and it was brilliant to see Jordan (Robertson) grab a late winner."
Blades: Willis, Scarisbrick, J. Williams, Whiteman, Salt, Banton, Dimaio (Eyre 77), Khan, McDonagh (Heather 71), Smith, Carrillo (Robertson 54).
Unused: Owen, T. Williams.