Two weeks after he stood on the touchline in Istanbul bristling with indignation, Amad Diallo walked barefoot across Old Trafford with a beaming smile on Thursday night, taking the applause from those fans who had stayed around to celebrate Manchester United’s first win in Europe for more than a year.

From sulky substitute to two-goal hero. Who knows what Ruud van Nistelrooy said to Diallo when he wrapped a consoling arm around him in Turkey as he prepared to come on in the 89th minute, but quite a lot has changed since then.

Van Nistelrooy has replaced Erik ten Hag as the man in charge of this team – for a few more days at least – and the scowl on Diallo’s face has given way to a grin.

Not that we should get too carried away, of course. This was another stodgy performance by United who started with £400million-worth of players against a PAOK team that only qualified for this stage of the competition after winning a play-off against Shamrock Rovers.

They played ‘Glory, Glory Man United’ at the final whistle but were fooling no-one. Old Trafford was emptying fast, there were swathes of empty red seats and the visiting Greek fans from Thessaloniki were still in good voice, as they had been all evening.

Amad Diallo stole the show with a superb performance as Manchester United beat PAOK 2-0

He put on a masterclass ahead of the arrival of new Manchester United boss Ruben Amorim

It was a crucial win for Man United, who were in dire need of their first Europa League victory

It was very different to the scenes that saw United’s new head coach Ruben Amorim swept out of the Estadio Jose Alvalade on a wave of emotion on Tuesday night after a barnstorming win over Manchester City in his penultimate game as Sporting Lisbon boss.

Amorim is leaving a team lying second in the Champions League and top of the table in Portugal for one that has climbed up to 15th in the Europa League and been struggling in the lower reaches of the Premier League.

He will start his new job on Monday with the bar set low thanks to games like this one as United laboured to victory thanks to Diallo’s two second-half goals on what was his first start for more than a month.

Did that motivate him? ‘Apparently so,’ smiled Van Nistelrooy. ‘He’s a great character and a hard worker. He shows it in every training session.

‘Every day he comes to me and wants to do extra finishing, crossing and one-on-ones. “How can I improve my shooting, my heading?” He is constantly focused on learning and very motivated to get the most from his career.’

Van Nistelrooy inherited a bad hand from Erik ten Hag and has played it to the best of his ability. United are now unbeaten in the three games since Ten Hag’s departure.

But very little has changed, in truth. There were too many similarities with the Europa League draws against FC Twente, Porto and Fenerbahce to think a corner has been turned.

Van Nistelrooy will take charge of Sunday’s game at home to Leicester City and then wait to see it he has a place in the new set-up. The indications are that he probably won’t.

Red Devils interim boss Ruud van Nistelrooy celebrates after Diallo’s sensational opener

Peeling away at the back post, the winger looped his header over the goalkeeper to score

Diallo’s second was just as sublime, curling his effort into the corner of the net from distance