David Weir suffered a first home defeat as Blades boss in Saturday's encounter with MK Dons.
Antony Kay's late header secured the points for the MK Dons although Jose Baxter made an encouraging start in a Blades shirt.
Febian Brandy wasted United's best chance - moments before Kay's winner - and the Blades winger was also sent off following a late tackle.
Boss Weir handed Baxter an immediate start after signing in midweek. The striker, brought in from Oldham in midweek, was one of three changes with Hill and Flynn also making their first league starts of the season. McGinty, McFadzean and Brandy all dropped to the bench.
Kicking towards the Kop in the first half, the Blades, with Baxter in the advanced midfield role, began well and Taylor almost connected with an early Murphy cross.
The first chance for the visitors arrived on 15 minutes but McLeod fluffed his shot after getting the better of Maguire, whilst a couple of niggles close to the dugout kept the officials - including the fourth official - busy.
Taylor shot across goal after Murphy nodded down a Doyle header and soon after Baxter volleyed wide after an encouraging link-up between Flynn and Taylor. The visitors also had opportunities in an even half, a Carruthers effort from the edge of the box was blocked by Maguire and McLeod fired over.
Two minutes of injury-time at the end of the first half brought a chance each before the interval. Baxter over-hit a forward ball as Taylor managed to wriggle clear and at the other end McMahon was well-placed to prevent McLeod getting in a shot from just six yards.
The Blades were first to register a chance in the second half when Baxter's shot deflected off Kay's leg to Taylor but his effort on the stretch was wide. Baxter also had another shot blocked within moments.
Teenage striker Ironside replaced Taylor before the hour and the replacement was involved in the move that resulted in Flynn getting booked, presumably for diving, when he went down in the box under Lewington's challenge.
The Blades fans were excited about the introduction of Brandy, who quickly won a free-kick which saw Martin have to palm away from McMahon. As the half progressed United continued to see plenty of the ball but were finding the Dons defence in resilient mood.
Ironside had another effort blocked as the final 15 minutes approached, whilst a weak effort from Dons' Bamford trickled wide. With eight minutes remaining Brandy got the better of his marker on the left and pulled the ball back for Ironside, but the fellow substitute steered wide under pressure but worse was to follow.
With five minutes to go Baxter got the better of Lewington and squared the ball for Brandy, who had the majority of the goal to aim at but he scuffed the ball wide.
And then, with three minutes remaining, there was further misery. From an inswinging Williams free-kick, KAY was positioned at the back post and headed home from close range as a wall of silence surrounded Bramall Lane.
Five minutes of added time gave Blades fans hope and McFadzean replaced Flynn but the Dons continued with their miserly defending and held on to secure the points, more comfortably after Brandy was sent off late on for a lunge on Hodson.
Blades: Long, Maguire, Hill, Flynn (McFadzean 90), Doyle, Taylor (Ironside 57), Baxter, Collins, Coady, Murphy (Brandy 64), McMahon.
Unused: Howard, Westlake, McGinn, McGinty.
MK Dons: Martin, Lewington, Hodson, Williams, Gleeson, Potter, McLeod (Chadwick 63), Bamford, Banton (Alli 71), Carruthers (Baldock 75), Kay.
Unused: Otsemobor, Smith, Reeves, Alli, McLoughlin.