The Blades are cruelly knocked out of the FA Cup, despite an excellent display at Old Trafford on Saturday evening.
England captain Wayne Rooney, with his only notable contribution of the game nets the winning goal from the penalty spot, after Dean Hammond fouled Memphis deep into stoppage-time, following a gritty display the visitors as they worked tirelessly to deny the Premier League giants.
For the third round tie against the Red Devils at Old Trafford, boss Adkins named an changed starting XI from the league clash against Peterborough United, although Matt Done was named amongst the substitutes having overcome a hamstring problem. For the home side, Louis van Gaal named a strong side, which included the likes of Rooney, Schweinsteiger, Fellaini, Mata and Martial.
Kicking towards the Stretford End, looking to beat Premiership opposition for the third consecutive season at the third round stage, the Blades started brightly with the away support in full voice. The Blades were defending resolutely at one end, whilst looking to break quickly at the other, McEveley's pass just evading the run of the marauding Woolford.
The home side's first effort on was wildly off target from Rooney, but moments later he got in behind United's defence from a Darmian pass and McEveley had to race back to snuff out the danger. Meanwhile, for the Blades, Coutts got the better of Fellaini on the right wing and forced Darmian into conceding a corner at the back post.
As the raining continued to pour down, the visitors were continuing to frustrate their more illustrious hosts as the game went past the half hour mark, although the Blades had two scares in quick succession. Firstly, Long was out smartly to deny Rooney, whilst Old Trafford appealed in vain for a penalty as McEveley challenged the advancing Schweinsteiger in the box.
A Rooney free-kick was blocked prior to three minutes added time being signalled, as Brayford stung the palms of De Gea at the other end. The last action of the first period came from another set-piece after Coutts fouled Martial, but Blind fired harmlessly over the bar from Rooney's cutback.
The second-half began with the rain having stopped and the Blades kicking towards the 8,500 Unitedites who continued to be in full voice. Still United defended gamely and van Gaal made a double change on the hour with Memphis and Lingard replacing Mata and Herrera, whilst Flynn took the place of Sharp moments later.
The first shot in anger of the second-half, much to delight of a frustrated home crowd, saw Memphis fire wide having cut inside from the left. At the other end, Basham forced De Gea into a save after a power run through the middle.
The introduction of Memphis had visibly given the home side and its supporters a lift, but still the Blades defended as a unit. McEveley limped out of the action and was replaced by Reed, with Woolford dropping into left-back.
The Red Devils were clearly nervy as the clocked ticked down and it showed as Smalling missed his kick completely with the goal at his mercy after Brayford had put his body on the line to deny Martial.
In the 93rd minute, just when it looked like a replay was on the cards, it was heartbreak for the Blades as Manchester United snatched what proved to be the winner from the penalty spot.
Memphis got the better of Brayford on the left and it was Hammond who was adjudged to have caught the Dutchman as weaved his way into the area. ROONEY stepped up from 12 yards and sent Long the wrong the way to cruelly send the Blades out of the cup.
Manchester United: De Gea, Darmian, Smalling, Blind, Borthwick-Jackson, Schweinsteiger, Fellaini (Pereira 78), Herrera (Lingard 60), Mata (Memphis 60), Martial, Rooney.
Unused: Romero, McNair, Varela, Keane.
Blades: Long, Brayford, Basham, Coutts, Sharp (Flynn 64), Collins, Woolford, Sammon (Done 90), McEveley (Reed 78), Edgar, Hammond.
Unused: Howard, Baxter, Campbell-Ryce, Adams.