Several Manchester United supporters headed for the exit in the 64th minute after the ball zipped past Andre Onana for a third time. They had seen this before. Just over a year ago.

United's decline and drift have gone on for so long it is not a shock for Bournemouth to be 3-0 up at Old Trafford. They won by that scoreline last December. They were three goals to the good 14 minutes quicker this time.

Bournemouth's fans began chanting, "You're f*****g s**t" and nobody of a United persuasion protested that. Ruben Amorim's nadir has come swiftly, a mere five weeks on from his first match in charge. The boos at full-time drowned out the supportive cry of 'Amorim's red and white army' from the Stretford End.

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Soon it was, "You're going down with the Scummers" - a reference to doomed basement side Southampton. Then, "You're going down with the City". United are heading towards the relegation zone with relegation form: three defeats in their past four Premier League matches and seven overall for the campaign.

This is the first time United have spent Christmas Day in the bottom half of the table since 1989. They are still marooned in 13th place and it does not do them a disservice.

Bournemouth and Brighton, two victors against United this term, are not just clubs in United's slipstream but model clubs they should aspire to emulate. Andoni Iraola has been one of the most inspired appointments by a Premier League club in recent memory and Bournemouth are serious contenders for the European places.

Amorim is not blameless in United's descent to potential relegation fodder. There were six more changes and the inclusion of Tyrell Malacia on the left wing was so charitable it was tantamount to a Soccer Aid selection.

The United head coach must stop playing full backs as wingers. Whether it is Malacia, Noussair Mazraoui or Diogo Dalot, they do not have the conviction as attackers to service a striker.

Amorim does not even believe in the striker he selected. Joshua Zirkzee's number was up after he lost another aerial duel and Amorim may think twice about rewarding players who perform in midweek cup ties.

Amorim signposted Marcus Rashford's omission in his programme notes that were filed early in the week when he reiterated "we have to work as one". Rashford was on his tod in the Old Trafford tunnel, clad in a club tracksuit, signing autographs for some star-struck mascots.

Unlike non-participating teammates Tom Heaton, Luke Shaw and Mason Mount, Rashford did not take a seat in the directors' box a few rows behind the United brains trust. There was plenty of room as the directors' box has seldom been so sparse. The broadcasters were unable to see him for some cinematic coverage.

Amorim swapped his £900 Paul Smith coat for a club design to insulate him from the Baltic chill. Rubbish zipped along the turf like one of the great United wingers. There was more rubbish from the players in red shirts.

Mazraoui was the first to be rebuked by the United head coach for positionally dawdling off the ball. Amorim's arms were soon outstretched in exasperation at a lateral pass from Kobbie Mainoo and Malacia for carelessly conceding possession. Malacia was hooked at half-time for the third time in his fourth start since returning from a knee injury last month.

That meant Mazraoui was shifted to the wing. Perhaps his panicky positioning contributed to the imbecilic lunge at Justin Kluivert that gifted the Dutchman the decisive spotkick. Kluivert, scorer of the first top flight penalty hat-trick since 1967 against Wolves recently, nonchalantly converted.

A United fan told Amorim's assistant, Carlos Fernandes, in Plzen last week that they need to stop crosses coming in. Fernandes replied, "We need to stop everything!" United are yet to make a start on that after they were breached from another set piece.

Dean Huijsen's header was as rudimentary a free-kick conversion as you could ever see. Zirkzee, purportedly Huijsen's marker, was never goal side and the header was expertly glanced into the far corner. It is the sixth successive match United have gone 1-0 down in.

United were not alive again for another dead-ball kick. Huijsen's effort marked the seventh goal United have sieved from a set piece in the Premier League this season and 17th this calendar year.

Andre Onana, back between the sticks, got stick from United fans for delaying attacks whenever he had the ball in his grasp or at his feet. That dilatory decision-making typified United's performance when there had been passages of progress against Manchester City and Tottenham.

Zirkee was as ineffectual aerially up the other end. His meek attempt to win Onana's punt in the 51st minute prompted Amorim to instruct Fernandes to ready the substitutes. Rasmus Hojlund and Alejandro Garnacho were soon waiting on the touchline.

United won a corner as Garnacho and Hojlund waited. Coaches usually wait to make their changes until after an attacking opportunity yet Amorim deemed the 6ft 4in Zirkzee to be no threat from Amad's inswinger.

Hojlund and Garnacho had their own openings. Garnacho offered a back-pass of a shot when one-on-one with Kepa Arrizabalaga and Hojlund could not find the target with his own sighter from distance.

Shortly after that, more fans departed in their droves. "We want four," the Bournemouth fans hopefully hollered.