Mousset, starting after Wilder opted to put Ollie McBurnie on the bench after he was charged with drink driving in Leeds on Friday, marked the occasion with a goal that undid in one fell swoop so much of the good work the Gunners had amassed in the opening weeks of the new campaign.

“I’m made up with the effort we put in. We knew they’d be vulnerable at set-pieces. We’ve said about matching performances to pick up points and we’ve done that,” said McBurnie.

The prospect of a fourth successive home defeat — something the Blades have not suffered since 1965 — was real and not one which Wilder would have wanted to contemplate; which made the timing of the opening goal and the manner in which his team opened the game all the more important.

Sheffield United went toe to toe with an Arsenal side beaten only by Liverpool so far this season and looking to move into the top three with a victory. And, despite at least one near miss, United were good value for the lead they took on the half hour following a left-flank corner from the busy John Fleck.

Jack O’Connell rose powerfully at the far post, capitalising on a slip by Matteo Guendouzi, and heading back into the six-yard area from where Mousset had the simple task of sweeping the ball home.

Bramall Lane erupted, sensing the latest potential chapter in the unlikely fairytale Wilder has delivered to the Blades support, but his opposite number was presumably less impressed with the turn of events and, specifically, his team’s defending.

It was the 22nd goal Arsenal have conceded from set-pieces since the start of last season — a tally “bettered” only by Watford and Everton in that time — and Emery had already been letting his frustrations show via a series of outbursts at the fourth official and sporadic verbal spats with the adjoining United bench.

When Bukayo Saka was booked after 35 minutes, for simulation after feeling the slightest of contacts from John Egan, the two dug-outs became embroiled in increasingly fractious discussion which ended with Gunners coach Freddie Ljungberg also being cautioned.

It was far from comfortable for Emery and his expensively assembled team, with the £72m (€64.5m) forward Nicolas Pepe contributing to Arsenal’s troubles by missing a glorious chance to put his side in front before the opening goal.

A devastating counter-attack, sprung in his own half by Saka, ended with Joe Willock slipping away Sead Kolasinac down the left-wing. The full-back’s cross looked destined to be converted by Pepe only for the Gunner to slide in and somehow miss contact.

Emery’s mood had also not been aided when Sokratis tumbled down, possibly with the aid of a tug to his shirt by Egan, in the early running and, after a solid if not exactly spectacular start to the campaign, this was turning into a litmus test of Arsenal’s resilience and durability.

The half might have ended on a more positive note for the visitors when Granit Xhaka waited for a bouncing ball to sit up perfectly and unleashed a 30-yard volley which Dean Henderson did well to keep out with a flying save.

Dani Ceballos was brought on for the ineffective Joe Willock, and Arsenal’s fortunes showed an instant improvement as they penned United into their own third. And Ceballos it was who was presented with his team’s first chance of the second period, appearing on the end of Saka’s tidy centre but succeeding only in planting the ball tamely straight at Henderson.

A couple of powerful shots from Fleck threatened the Gunners — one flying into the side-netting, the other from fully 30 yards being gobbled up by Bernd Leno — but the visitors were firmly in control. The increased pressure showed when David McGoldrick became the second player on the night booked for simulation after he dived under zero contact from Guendouzi in a bid to buy some much-needed relief.

Pepe stood over a 25-yard free-kick 17 minutes from time but succeeded only in lifting it over the wall and into the waiting arms of Henderson, while he sent a curling left-foot shot wide moments later. Calum Chambers was presented with the last meaningful chance of the night but could only drive a cross-shot through a crowded United penalty area — a symbolic end to a frustrating Arsenal night.

Sheff United (3-5-2):

Henderson 8; Basham 7, Egan 7, O’Connell 7; Baldock 7, Lundstram 6, Norwood 6 (McBurnie 85), Fleck 9, Stevens 7; McGoldrick 7 (L Freeman 78, 6), Mousset 7 (Sharp 55, 6).

Subs: Robinson, Jagielka, Moore, Besic.

Arsenal (4-2-3-1):

Subs: Martinez, Holding, Tierney, Torreira

Referee: Mike Dean 7