On a sombre afternoon graced by a piper’s rendition of Flower of Scotland and a poetic tribute to the great man, Manchester United went down dismally in their first game since Friday’s passing of Denis Law.

Ruben Amorim’s 15th match piloting United enters the record books as a seventh defeat. Afterwards his declaration was damning, branding his side as the poorest “maybe in the history of Manchester United”.

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How this will boost the confidence levels of players the Portuguese describes as “nervous” is a puzzle. He may also wish to halt that characterisation as constantly outing them in public as jittery is no Winston Churchill-like call to arms.

Amorim’s view is that honesty is the best way to rouse his charges but he may like to consider altering the Ange Postecoglou-esque insistence that he will not change a 3-4-3 system that has his side as muddled as Erik ten Hag’s vintage, and which is from a “new coach who is losing more than the last”.

As in Thursday’s win over Southampton here, United had chances towards the end to stage a ­comeback but when struggling you do not require a howler from your ­goalkeeper to gift the opponent a two-goal cushion.

On 76 minutes, André Onana did precisely this. Yasin Ayari, who starred throughout, swept the ball in from the right. United’s keeper went to ground and saw the ball slip from his gloves to Georginio Rutter. The substitute evaded the despairing Cameroonian and rolled home.

After adding the latest clownish error to a bulging catalogue, Onana lay prone, head on the turf, having provided a bookend to United’s performance as unwanted as the side’s concession at the start.

Amorim’s side were cast as hapless bystanders for Brighton’s early opener, breached in a fluid back-to-front move that was too easy for the visitors to execute. Carlos Baleba lifted the ball from his half to the marauding Kaoru Mitoma along the left. He danced forward, steered the ball across, and Yankuba Minteh’s finish came with the home rearguard awol.

United were rocked. Amorim threw his hands in disgust. Five minutes played and those in red were already squeezed behind the white ball. Studding the display was Noussair Mazraoui three times spilling the ball to Brighton, an aimless Bruno Fernandes pass and Amorim’s men being outmuscled too often in 50-50s.

But, they probed and after several home congregation calls of “foul” for differing Brighton challenges that were ignored by Peter Bankes, the referee pointed to the spot when Baleba hooked an arm around Joshua Zirkzee, the striker hitting the turf. Fernandes sent Bert Verbruggen falling to his left, placing the penalty to the keeper’s right and the scores were level.

Zirkzee is a curious footballer. The Dutchman can be clumsy-footed and silken of touch in the same moment, as when the ball came to him near halfway, he diced with losing it, applied balletic feet to swerve two markers, and ignited an attack. This drew applause, perhaps from some of the same constituency who booed him off when replaced after 32 minutes against Newcastle last month.

Amorim’s desire to transform United into a unit akin to Fabian ­Hürzeler’s requires time and his players to buy into this. Winning is the best way to guarantee they do. Yet they came close to going behind again before the break. Leny Yoro slipped in front of his area and suddenly a block was needed to keep Danny Welbeck from scoring.

Stability is no apt word for United and so after they began the second half brightly – when Amad Diallo roved in and unloaded – you waited for a hole to be punched through them by Brighton. Moments later it came: João Pedro smashed home after more amateurish defending from an Ayari free-kick.

The Swede slipped, the ball bobbled about in the area, and Brighton’s No 9 hit the net. Yet now a reprieve arrived for United as Bankes, sent to the monitor by the VAR, adjudged Jan Paul van Hecke to have kicked Diogo Dalot’s foot in the buildup. The goal was ruled out.

Then came calamity. An Ayari sprint took him clean through United’s sleepwalking midfield. His pass went to Minteh on the right. He flipped the ball over and Mazraoui’s torrid afternoon now featured a failure to prevent Mitoma bundling home at the far post.

Immediately Amorim took off Manuel Ugarte and Kobbie Mainoo for Toby Collyer and Alejandro Garnacho. Onana’s despair was to follow. After eight minutes of stoppage time, at the final whistle United had again failed to register back-to-back Premier League wins.

England’s record 20-times champions remain stuck at their ­latest crossroads. The current vintage is several galaxies away from Matt Busby’s brilliant 1960s one that was decorated by the supreme winner Law.