United deservedly progressed to the second round of the FA Youth Cup following a thrilling victory over Crewe Alexandra at Bramall Lane.
The Blades trailed at the break, but second-half goals from Jordan Hallam and George Cantrill in stoppage-time saw the home side win a game they dominated from start-to-finish.
Crewe were quickly out of the blocks and after forcing a couple of early corners, they took the lead in bizarre circumstances in the fourth minute. Perryman's attempted clearance was charged down by WALLEY and it bounced twice before hitting the roof of the unguarded net.
United's response was positive, Hallam laid off for Greaves to shoot at goal, his effort was blocked, before Smith saw an effort deflected wide for a corner, from which Burton headed over at the back post.
In the 26th minute, having grown into the contest, United had two opportunities to equalise inside 60 seconds. Firstly, from a Greaves cross Smith missed his kick with goal at his mercy, before Cummings powered a header over from Gilmour's pinpoint delivery
The Blades were now firmly in the ascendency despite being behind and after Slater had robbed Lundstram, Smith stung the palms of Wardley from distance. The Crewe stopper was then called upon again moments later this time making a better save to deny Slater from outside the penalty area.
As half-time approached, Cantrill became the first player to be booked, for an overenthusiastic challenge on Woodcock. Before the break, Cummings flicked on Cantrill's long throw at the near post, but unfortunately for the home side nobody was on hand to apply the finishing touch despite the best efforts of Hallam.
And with the last action of the first period, goalkeeper Wardley punched against his own crossbar after Hallam's free-kick wasn't cleared properly.
As was the case in the first-half, the Railwaymen begun brightly after the break, with Dale firing inches wide of Perryman's far post, prior to Reilly seeing yellow for a late lunge on Cummings.
In the 56th minute, the Blades had strong appeals for a penalty waved away by referee Dallison after Wilkinson appeared to clip Smith's heels as he prepared to shoot.
On the hour, Crewe made a substitution with Griffiths replacing Walley, in search of an equaliser Cantrill volleyed over the bar from a Cummings knockdown. Dale then become the second opposing player to be booked for dissent.
With 19 minutes remaining, both sides made a change. Mallon replaced Greaves for the Blades, whilst Harrison took the place of Lynch for the Alex. And two minutes later, the Blades deservedly restored parity. Smith's shot hit the post, but the rebound fell perfectly for HALLAM to tap-in from close-range. In the aftermath of the goal Burton was booked for a tangle with Wardley.
The Blades were now sensing a winner and only the intervention of the linesman flag denied them the lead, as Gilmour was adjudged to have been in an offside position as he fired home with his left foot. Next to be denied was Burton, who saw his placed header hit the crossbar and go over from Smith's inviting cross. From the left.
The home side were mounting the pressure, Burton fired wide with the goal at his mercy, then Hallam curled an effort inches wide with Wardley rooted to the spot. Finally, though as the clock ticked past 90, United got the winning goal their efforts deserved. Good work by Mallon and then Smith fashioned an opening and CANTRILL was there to firing into the empty net.
Blades: Perryman, Charlesworth, Cantrill, Gilmour, Cummings, Graham, T. Smith, Slater, Burton (Parkhouse 90), Hallam, Greaves (Mallon 71)
Unused: A. Brown, Warhurst, Ford.