Through the winter mist of a North London afternoon, it was possible to see the green shoots of Manchester United recovery. Just the tips. There is a long way to go and for sure there will be some setbacks along the way.

But from the horrors of Nottingham Forest, Wolves, Bournemouth and Newcastle, Ruben Amorim’s players have somehow managed to inch their way forward when few expected it. Perhaps more importantly than anything, they have rediscovered a little of their self-respect and their belief.

They needed tonnes of all that here at the Emirates. They played an hour of football with ten men. They played an hour almost exclusively in their own half. Diogo Dalot’s dismissal for two quick second half bookings seemed to have killed them.

And when Bruno Fernandes’ goal was cancelled out by Arsenal defender Gabriel within a minute of Dalot exiting the scene, it seemed inevitable that Mikel Arteta’s team would run all over United.

And it could have happened. It probably should have happened. Had Martin Odegaard not fluffed a penalty – Altay Bayindir saving – soon after Gabriel’s goal then it almost certainly would have.

Yes, Arsenal missed their chances. Lots of them. If ever there was an illustration of their enduring need of a centre forward then this was it. This has been a bad week for Arsenal and in particular their up and down German forward Kai Havertz.

But United did not survive through the rest of the second half and then a period of extra time to eventually prevail on penalties just because Arsenal were feckless in front of goal.

They did it because their three central defenders – Harry Maguire, Matthijs De Ligt and Lisandro Martinez – were sensational both in effort and deed.

They did it because back up goalkeeper Bayindir – at fault as United exited the Carabao Cup at Tottenham last month – decided that this was going to be his day.

They did it because they were committed, determined and, yes, united. Too often in recent years United have played as though they were a man short.

They have made eleven feel like ten or even nine. Here, they pulled off the opposite illusion. Here they made ten seem like eleven and you don’t do that without an awful lot of running and hard work.

And they also did it because, when it came down to it, they held their nerve in a shoot-out when Arsenal didn’t and the identity of the winning taker was particularly appropriate.

Everybody had scored apart from the hapless Havertz when Joshua Zirkzee stepped up to take United’s fifth penalty. It seemed a brave choice by United manager Amorim.

Zirkzee had been booed off by his own fans when United lost to Newcastle at Christmas and some people even blamed him for not providing Maguire with a perfect pass when glory beckoned towards the end of the 2-2 draw at Liverpool last week.

So this seemed like a bang or bust decision by Amorim. Time to watch through your fingers. But if Zirkzee was fazed he didn’t show it, rolling the ball calmly to David Raya’s right to send United in to the next round and to repair his own damaged reputation with one simple act. Nice.

For Arsenal this felt sobering. Beaten here 2-0 by Newcastle in the Carabao Cup in midweek, they were not good enough once again. They didn’t create a proper chance in the first half and only came to life when they had an extra man. To make matters worse, they lost Gabriel Jesus to first half injury.

They know why they lost. They missed too many chances. Equally, there was not enough calm about their football. They were not incisive. They were too often hopeful and not often enough assured. Their much-celebrated set pieces were terrible. High and looping. Coming down with snow on.

In the first half nothing happened. Arsenal had the ball and the territory but United the two shots on goal, from Kobbie Mainoo and the recalled Alejandro Garnacho. And then, in the second half, everybody and everything woke up.

First, in the 52nd minute, Fernandes scored. Arsenal defender Gabriel lost a dual with Garnacho in front of the dug outs and ran clear to square to his captain who scored beautifully first time with his instep. A fabulous goal.

Arsenal’s response was purposeful. Raheem Sterling – on for Jesus – and Havertz both could have equalised almost immediately but snatched at their shots. The anxiety levels at the Emirates cranked up a notch.

But then Dalot lunged at Mikel Merino – having been booked twelve minutes earlier – and was sent off. He made no contact but was reckless. Arguments ensued and as the temperature rose Arsenal equalised. Bayindir could only punch an in swinging free-kick up in to the air and when the ball dropped and bounced, Gabriel showed great technique to turn and volley in to the corner via a deflection off De Ligt.

Arsenal’s penalty soon followed and was dubious. Maguire seemed to withdraw his leg before Havertz fell over it. In the melee that followed – Havertz falling after some shoving with Garnacho and possible use of the head by Manuel Ugarte – Maguire made his feelings known. Odegaard – normally so calm – took the penalty and – diving to his left – Bayindir saved it.

Arteta’s team still had time and chances to win it in regulation time. Declan Rice – on as a substitute – came close twice, once with a header and then with a low shot. Bayindir saved both. Then, in extra time, Havertz missed from six yards and De Lijt cleared from the toe of Leandro Trossard when the Belgian looked set to win it.

The longer it all went on the greater the sense of inevitability became. O]degaard was composed enough to take and convert his team’s first kick in the shoot-out but Havertz flunked Arsenal’s second – Bayindir saving easily – and United went through thanks to Fernandes, Amad, Leny Yoro, Martinez and, finally, Zirkzee.

Amorim was away down the tunnel almost immediately. No wild celebrations for the United manager. Just another step on the road. His United tenure – that now stretches to thirteen games – has not been dull.