A very late goal cost United on the road at Swindon Town.
Michael Doyle cancelled out Miles Storey's first half goal and the Blades were the better side in the second half before getting stung with a sucker-punch from Louis Thompson.
United were good value to get something out of a second long trip of the week but in the end saw the six match unbeaten away record come to an end.
Like midweek, chief Clough made three changes. Flynn, Scougall and Baxter all returned after being rested at Crawley. Maguire missed out due to suspension, an accumulation of yellow cards, whilst Porter and McGinn dropped to the bench.
After a delayed kick-off due to an accident close to the County Ground, it was quickly evident that Brayford was the auxiliary central defender, lining up alongside Collins - Davies slotted in at right-back and Freeman continued at left-back.
In a slow start, Swindon's Michael Smith was the most prominent player of the opening ten minutes. He had a shot blocked by Freeman early on and then was twice denied in the air by Collins as he looked to give the home side a boost.
United's only effort of note in the early exchanges was Brayford firing over after a corner had been half-cleared before Swindon opened the scoring on 18 minutes. Michael Smith was again involved, this time playing through the defence for STOREY to latch on and beat Howard with a shot into the top corner.
Despite having plenty of possession, United were struggling to test goalkeeper Foderingham and just after the half hour the visitors were forced into a change when Baxter hobbled off - Porter was the replacement.
Foderingham was then tested twice inside the space of a minute following two set-pieces, delivered by Davies. The first, on 36 minutes, was a free-kick which Coady met but the goalkeeper pushed away and from the resulting corner Brayford lost his man but again the custodian was ideally placed deflect clear.
Collins headed over another Davies free-kick as half-time approached but the Blades were unable to get back on level terms before the interval and continued to force Swindon back in the early stages of the second period, which resulted in the home side picking up a couple of bookings.
Swindon almost hit the Blades on the break on 56 minutes, a slip gave Michael Smith space but he pulled his shot wide and the visitors took advantage, levelling with the next move. Murphy and Freeman combined on the left before Scougall played across the box for DOYLE to arrive late in the box and tap in at the back post. It was Scougall's last contribution as he was replaced by McGinn moments later.
Porter headed over a Davies corner as the final 15 minutes approached, the Blades looking the more dangerous and there was an appeal for a penalty turned away when Freeman went down under a Archibald-Henville challenge.
A half-volley from Doyle on 82 minutes, which could not have been far wide of the top corner, emphasised the fact that United were on top and Porter almost got on the end of a McGinn pass but Foderingham was quickly off his line.
There was a moment of confusion on 88 minutes when Flynn was fouled as he put the ball through to Porter who finished neatly. However, the striker was adjudged to be offside and referee Hill pulled back the action and handed United a free-kick, which Davies blasted into the wall.
After that Foderingham produced a tremendous reaction save from Coady following Porter's cross, before disaster struck. The Blades wanted to win and were committing players to the attack but on the break a number of red shirts descended on the United goal and Louis THOMPSON's shot squirmed away from Howard and the spin managed to carry the ball over the line.
Five minutes of added time gave United hope. Davies was booked and Paynter was introduced but Swindon survived to collect the points after Foderingham collected a Collins header.
Swindon: Foderingham, N. Thompson (Byrne 67), McEveley, Kasim, Storey, A. Smith, Cox, M. Smith (Waldon 80), Gladwin (L. Thompson 62), Stephens, Archibald-Henville.
Unused: Belford, Barthram, Rossi-Branco, Barker.
Blades: Howard, Brayford, Flynn, Doyle, Baxter (Porter 33), Collins, Coady, Scougall (Scougall 59), Davies, Murphy, Freeman (Paynter 90).
Unused: Long, Khan, Kennedy, Dimaio.