United lost to City who gained revenge in the sweetest manor by slamming three goals past an uneducated defence in the space of 18 minutes with the Blades showing little effort or encouragement to find a way back into the game.
Why it went so wrong may be unanswerable; but playing a formation of 4-5-1 which, true to form has worked well away from home surely can't be mastered on your own back yard - many teams have tried and failed in the past and last night was no exception.
The Blades had only lost once in their previous nine outings prior to their clash with Coca-Cola Championship rivals Stoke but somehow made a mess of a game which could have put them somewhere in or near the play-off zone.
United won at the Britannia Stadium 1-0 just three weeks ago with Gary Cahill netted the decisive winner; but all that hard work seemed undone when only two minutes into the game at Bramall Lane Liam Lawrence latched unmarked onto Ryan Shawcross' free-kick to find time and space to square the ball across goal and into the path of former Sheffield Wednesday striker Richard Cresswell who tapped home.
Defensive blunders was the key to this defeat but I couldn't help but feel sorry four minutes later when City doubled their lead. Lawrence turned provider once again has he powered in a free-kick to the far post which cruelly bounced off the head of James Beattie and into his own net.
Beattie, who is currently chasing his 13th Championship goal of the season has obviously found it an unlucky number as his defensive duties backfired.
And, on 19 minutes the uneven back four once again crumbled with Lawrence providing the vital blow, the former Sunderland midfielder swung in another free-kick for Cresswell to head but the ball somehow smashed against Shawcross with Paddy Kenny watching as the ball spiralled into the net.
From then on United were down and out with City creating little further effort - Blades boss Bryan Robson attempted to make emends of his early bad decision to to play one up front by throwing Jonathan Stead into the mix as early as the 22nd minute but United lacked confidence which had been drained out of them by three conceded goals and created little chances to worm there way back into the game.
City could have made it four-nil in the second half with Kenny bravely saving Ricardo Fuller's effort as he weaved in the box to shoot from 15 yards.
Despite the ring of much needed changes it took until 70th minute for Potters keeper Steve Simonsen made his first save of the game - on-loan defender Phil Bardsley found Michael Tonge wanting and the midfielder struck a low fierce shot which the keeper managed to get down low and hold.
The performance was less than impressive and seen as unacceptable by Blades fans who saw there team succumbed to their second home match in a row - with important games against Norwich City away and a South Yorkshire derby against Barnsley at Bramall Lane it seems pretty obvious that things need to change.