To have defeated the Red Devils on Saturday might have been a bit like telling a tasteless joke at a wake and although it did not stop the Blades trying, manager Paul Heckingbottom reminded everyone afterwards of the footballing context.
"We're not in a league against Manchester United," he said because sometimes in football even the bleedin' obvious needs restating.
Both Uniteds kicked off in a bad way psychologically and physically.
Whereas for the Blades it meant being winless and bottom of the Premier League, drifting another point from safety as Luton Town drew at Nottingham Forest in the afternoon, for their guests it just meant sitting in mid-table with work to do to qualify from a Champions League group where even the losers coin it in.
Sheffield United's bench featured Ryan One, Femi Seiki and Jill Buyabu, a wing-back whose name will now have to be added to the squad list on the back of the programme. Their guests brought on a World Cup winner (Raphael Varane), a £55m summer signing (Mason Mount) and a striker they once valued at £36m (Anthony Martial).
Donny van de Beek, a £35m signing three years ago, and Facundo Pellistri, who would surely be in the Blades' first team had his parent club loaned him out, did not get on.
So there was no shame in losing 2-1 to a goal from a midfielder, Scott McTominay, who like Charlton came through Manchester United’s youth set-up and a Diogo Dalot howitzer worthy of the man with gunpowder in his boots.
Even so, their position means the Blades need to start take something from these games and in lieu of points, Saturday's perhaps uncovered an alternative path.
Apart from a brief divergence under Slavisa Jokanovic, 3-5-2 has been an article of faith at Bramall Lane for years. Chris Wilder took the Blades from League One to ninth in the Premier League with overlapping centre-backs and wide overloads but since what turned out to be a career-ending knee injury to Jack O'Connell in 2020, neither the club nor Wilder have been able to recreate the magic. Anything is only new once.
Anel Ahmedhodzic showed last season he can be a buckaneering centre-back but in the last two Premier League campaigns the club has felt too under the pump to unshackle them, and John Egan's season-ruining Achilles injury dictated a more reserved central role until Ahmedhodzic twanged his hamstring in training last week.
Football history is littered with stories of forced experiments redefining careers and occasionally clubs, and with Auston Trusty and Jack Robinson his only fit centre-backs, Heckingbottom felt compelled to play old-fashioned 4-4-2.
Previous Blades back fours have been topped off with diamond midfields but on Saturday it was flatter with Gustavo Hamer and James McAtee wide, the former often cutting infield to find the latter.
"We could (have Hamer and McAtee in a 3-5-2) but I don't think our set-up's strong enough against the ball," said Heckingbottom, who considered a switch before Ahmedhodzic joined his relentless injury list.
"We've gone from the second best in the top five leagues in Europe in terms of high regains to chances, we lost a lot of players who were part of that (by selling Iliman Ndiaye and Sander Berge) so we've had to adapt.
"What you'll tend to see, whatever we play, certainly when it's a back four, is when we have the ball it won't look any shape really but without the ball, that's where the structure will come."
The Blades were the better team for the first half-hour, Oli McBurnie and Cameron Archer forcing saves. Vinicius Souza's fourth-minute glide past McTominay from the centre showed their confidence against opponents struggling for rhythm.
But McTominay outmuscled Oliver Norwood to score a scrappy opener after 30 minutes and although McBurnie – already struggling with the groin strain that forced him off early in the second half – gave Andre Onana no chance with a penalty minutes later, Manchester United had found some mojo and the hosts had little on the bench to reinvigorate them.
The Blades looked harder to break down defensively without rationing ambition to a bare minimum as against Manchester City and Tottenham Hotspur but the Red Devils still hit the woodwork in either half – Bruno Fernandes from a free-kick, Sofyan Amarabat a snapshot.
An away goal felt like it was coming and the dominance allowed both full-backs to be high up the pitch when Victor Lindelof pulled the ball back for Dalot, lurking in a lot of space to unleash in the 77th minute.
His 4-4-2 had not worked either for Heckingbottom, but as he clutched at positives as he must in difficult times this was worth grasping, and possibly running with.
Sheffield United: Foderingham; Bogle, Trusty, Robinson, Thomas; McAtee (Osborn 78), Souza, Norwood, Hamer (Traore 84); McBurnie (Brewster 51), Archer. Unused substitutes: Fleck, Slimane, One, Seriki, Buyabu.
Manchester United: Onana; Dalot, Maguire, Evans (Varane 84), Lindelof; Amrabat, McTominay (Eriksen 63); Antony (Garnacho 63), Fernandes, Rashford (Mount 87); Hojlund (Martial 63). Unused substitutes: Bayindir, Pellistri, van de Beek, Mejbri.
Referee: M Oliver (Ashington).