Even when they raised some late hope, with Oliver Giroud, back from injury, striking an exquisite half volley in added time, it was illusory.
The fact that they could contrive to lose to such a weakened United side in a game which they might have had wrapped up within 20 minutes was stupefying. And their sheer absence of ruthlessness indicates just how fragile they have become: a mentally-flawed team that has turned losing games from dominant positions into an art form.
‘It was a game that we dominated for 80 per cent of the time and it’s a long time since we have dominated games against Manchester United like we did today,’ said Wenger.
‘But we were not efficient enough in the final third and we made a mistake at the back. We had plenty of chances: their keeper is man of the match and that tells you the story of the game.’
Louis van Gaal’s brazenness is generally characterised as genius; it looked closer to madness in those opening 20 minutes as United flailed in defence. A back three of Paddy McNair, Chris Smalling and Tyler Blackett was encouragement enough to Arsenal and within 15 minutes United had also lost Luke Shaw to injury.
Wenger’s side attacked like a team that knew they were in the ascendancy, Alexis Sanchez leading the way, playing with an intensity which was exhilarating.
The chances came in a flurry: a free header for Per Mertesacker; a header over from Danny Welbeck after superb play from Alex Oxlade-Chamberlain; a shot from Jack Wilshere, after he drove through a vacant United midfield.
But principally there was Wilshere’s chance on 15 minutes, created by Sanchez chasing down David De Gea, whose consequent weak clearance reached only Welbeck, who fed Wilshere.
Charging through United’s defence again and this time less than six yards out with only De Gea to beat, Wilshere hesitated before shooting into the United goalkeeper’s body: it was a terrible miss.
‘I was not pleased with the way we had played in the first half,’ Van Gaal said. ‘I have to say the first 25 minutes we gave the ball so easily away, it’s not possible for a top team. Arsenal created a lot of chances, but fortunately we have a very good goalkeeper in David De Gea
‘If Arsenal had score in the first 20 minutes, it would have been another game and then maybe I would have had to respond to all the questions because I had chosen three defenders - but now I can laugh.
Wilshere’s miss proved significant, as United slowly began to settle and Wilshere it was who was un-nerved enough on 30 minutes to butt his head into Marouane Fellaini’s chin. He was lucky to stay on the pitch, let alone not even earn a yellow card.
Arsenal started the second half well, with Oxlade-Chamberlain delivering a delightful ball for Welbeck, who found his way blocked again by De Gea. Try as he might, Welbeck could not punish Van Gaal for his lack of faith in his talent. And shortly after Wilshere had to depart with an ankle injury after a terrible challenge from McNair.
And yet Arsenal are always only a moment away from calamity. An Ashley Young cross on 56 minutes was directed at a marginally offside Fellaini but Kieran Gibbs and Wojciech Szczesny got themselves in a terrible mess, colliding and knocking each other over. Antonio Valencia fired in a relatively harmless cross, but Gibbs inexplicably lifted his leg while still grounded.
With his goalkeeper still struggling, winded and injured, Gibbs diverted the ball into his own net. Worse for Arsenal, Szczesny had to come off immediately after the goal with Emiliano Martinez replacing him.
Suddenly Smalling looked a leader, making crucial interceptions and pulling McNair and Blackett into shape. There was a Sanchez header on 63 minutes and a fine Santi Cazorla strike on 69 minutes, but then Arsenal lost the ball on the edge of the United box on 86 minutes - they are never more of a danger to themselves than when on the attack - and Fellaini swept the ball to Angel Di Maria. He advanced it on to Wayne Rooney, who finished with a cool confidence. Wenger was unimpressed.
‘It was just after a corner and we were not cautious enough,’ he said. ‘I don’t know why we had nobody at the back at all.’
It might have been 3-0, Di Maria chipping wide when he seemed sure to score from another breakaway. Giroud then provided his late riposte, but such finery could not disguise Arsenal’s failings.
‘There’s discordance between possession and the chances we create and our results,’ said Wenger. ‘It’s very difficult but we have to keep faith in what we do.’
