United's Under 18s played out a six-goal thriller against Hull City but the East Yorkshire side denied for the Blades for a second time in 24 hours with a late equaliser after United had overturned a 2-0 deficit during the second half.
Two goals from Zak Brunt either side of Leo Gaxha's strike appeared to have handed the Blades three points but Ben Adamson's stoppage time strike ensured another stalemate.
It was a point though the Blades could hardly turn their noses up at after falling 2-0 behind inside the opening 10 minutes as Hull made their aerial advantage count.
Andy Smith towered above the United defence inside five minutes to head home a free-kick before Rob Guilfoyle also headed home a cross soon after to put the visitors in control.
But from then on Josh Chapman - making his Under 18s debut - had little to do as United took control of the match in their search to make a comeback.
Brunt was at the heart of it and almost pulled one back instantly with an effort from distance before Gaxha and Tom Williams also tried their luck from range, both seeing their efforts go behind for a corner.
Gaxha went closer still, curling just wide from the edge of the box before Sammy Ompreon headed Jake Kelly's cross.
United were finding all sorts of space on the edge of the box so it was no surprise when Brunt finally found room and curled home an effort from just outside the area to make it 2-1 before the break.
The onslaught continued immediately after the restart when Andre Brooks forced a save inside 20 seconds and United were level on the hour when the Hull goalkeeper dropped a corner right at the feet of Gaxha who swept home the opportunity gifted to him.
And it looked like United had won it with three minutes to go when Brunt turned his marker inside the box and fired home via a small deflection to make it 3-2.
But there was one final twist when Adamson found himself free on the edge of United's box, Chapman got a hand to his effort but the ball nestled in the bottom corner to make it 3-3.
Blades: Chapman, T. Wilson, Brooks, Williams, Foulstone, Gomis, J. Kelly (Viggers 89), Maguire, Gaxha (Hackford 86), Brunt, Ompreon (Ackroyd 73).
Unused: S. Kelly.