Entertaining mayhem could come at a cost to United. Ahead 1-0, 2-1 and 4-3, they missed the chance to go fifth and extended an undistinguished run at home. Ten-man Everton won at Old Trafford, relegation-threatened West Ham drew and so, in ludicrous fashion, did out-of-form Bournemouth. What could have been nine points at Old Trafford is instead just two.

And yet to concentrate on the wider ramifications would be to overlook the eight goals that came amidst the bemusing, confusing drama. It may have been fitting that the last of them came from Bournemouth, Eli Junior Kroupi coming off the bench to procure Andoni Iraola’s side a point. It still required two saves from Senne Lammens to stop David Brooks turning that into 5-4 win for Bournemouth.

What may be said is that Amorim’s change of shape benefited United in attack but definitely not in defence. Even as they scored four for a second successive game, they looked liberated, freed from Amorim’s tactical straitjacket. Energetic and attacking, they had 11 shots in the first 25 minutes alone, 25 in total, an xG of 3.27. They got more players forward; indeed Amad Diallo, not a natural wing-back, was given a more advanced role in a lopsided 4-4-2 and that felt a reason why he could open the scoring.

Yet for much of the evening, it seemed a case of chaos rather than structure. Bruno Fernandes has long had a galvanising influence with force of personality more than managerial design. He provided United’s second goal – a seventh assist of the Premier League campaign giving him more than anyone else in the division – and scored the third with a wonderful free kick, his own third goal in eight days.

Amorim may taken particular pleasure from United’s fourth goal: a combination of two of his summer signings with Benjamin Sesko, making his comeback after injury, setting up Matheus Cunha to score just his second goal since his £62.5m arrival.

Though, when all that is said, United could be grateful to Djordje Petrovic for his generous goalkeeping, a factor in their first two goals. He parried Cunha’s header to Amad to finish from close range and then allowed Casemiro’s effort to slip through his hands.

Nevertheless, their attacking endeavours offered vindication for Amorim’s formation change. It felt an admission he had been wrong for 13 months. It looked that United were being hindered by dogma. Yet, unpractised in a shape previous managers preferred, they could not defend.

After bringing a back four, they conceded four. Antoine Semenyo and Evanilson arrived in the midst of goal droughts. Each was ended.

And Andoni Iraola, whose name echoed around Old Trafford, deserved much of the credit. There were two tactical rethinks: one by Amorim before kick-off, one by Iraola after it. Amorim had put Leny Yoro in a contest with Semenyo, so Iraola swapped him to the opposite flank to run at Luke Shaw. It was as a right winger that he levelled, surging clear to drive in a shot.

But United led at half-time and, when they do in a league game at Old Trafford, they have not lost since 1984; or, in other words, in Amorim’s lifetime. Nine awful minutes put that record under threat. Thirty seconds after the interval and played onside by Ayden Heaven, Evanilson latched on to Justin Kluivert’s pass to score a first goal in 11 games.

Then Marcus Tavernier curled in a low free kick, conceded by Casemiro with a desperate foul on the eventual scorer. Lammens was also culpable as he probably should have saved it.

It was a third consecutive season that Bournemouth scored at least three goals at Old Trafford. They had only five goals at Old Trafford in their history before getting 10 in three trips. “Man United, it’s happened again,” chorused the visiting fans after Tavernier struck.

This time, they did not win. This time, however, they got four, courtesy of Junior Kroupi. For United, a 4-4-2 brought a 4-4. It had seemed the great certainties were death, taxes and Amorim’s insistence on 3-4-3. Even the Pope, he had said, could not make him change that. Whether or not papal intervention is required, however, a newly flexible manager’s next task is to get United winning at Old Trafford again. (© The Independent)