Brentford gave a nod to what has become known as Star Wars Day, and it felt as though May the Fourth was destined to belong to a young man called Obi. But we should have guessed that Manchester United would show their dark side again.

Flying in the Europa League and pants in the Premier League, it has become a depressingly familiar storyline for Ruben Amorim and his players.

This time it was a vibrant Brentford who benefited from United’s Jekyll and Hyde season to boost their hopes of European qualification. It’s no surprise Ineos considered Thomas Frank before they appointed Amorim in November.

United may finish the season with a European trophy, but at what cost to their dignity at home? They are in 15th position in the table and could finish just one place above the drop zone.

Three days after a rousing semi-final win over Athletic Bilbao in Spain, Amorim made eight changes and was brought down to earth again by another team in red-and-white stripes.

Don’t be fooled by the scoreline and two late goals from Alejandro Garnacho and Amad Diallo that threatened an unlikely comeback here. Brentford were better by some distance as they won for the third game in a row to go ninth.

Kevin Schade scored twice to move onto 10 league goals for the season, and Yoane Wissa joined Bryan Mbuemo on 18. Mbuemo showed once again why he could be of interest to United this summer.

‘As far as I know Mbuemo is still with us,’ smiled Frank when asked about the speculation.

‘Now we have three players who have scored 10 goals or more; 46 between the front three is an unbelievable number. To have that in any club is incredible, but for us to have it is an even bigger achievement.

‘We really, really believe we can win every game. We respect everyone but fear no-one.’

In contrast, Amorim’s attacking options were so limited that he could only turn to teenage striker Chido Obi as he tried to protect Rasmus Hojlund and other key players ahead of Thursday’s return leg against Bilbao at Old Trafford. United may be 3-0 up, but you can’t take anything for granted with this team.

At 17 years and 156 days, Obi replaced Mason Greenwood as the youngest United player to start a Premier League match in what was also the club’s youngest-ever team in the competition.

In truth, he struggled and so did Tyler Fredricson and Harry Amass.

Fredricson had a tough afternoon against Schade, Amass was under the cosh on the other side of defence, and Obi’s big moment came and went when his shot from close-range was blocked in the second half.

‘Chido fought all game but he’s really naive sometimes in the way he puts his body,’ said Amorim, who is waiting to assess an injury to Matthijs de Ligt and also took off Luke Shaw at half-time as a precaution before the return leg.

He feared that making so many changes would leave United vulnerable to Brentford’s height, and that was an even bigger problem when De Ligt went off in the 35th minute after Brentford had cancelled out Mason Mount’s opener.

After they had finished playing the Star Wars theme tune and United had weathered early pressure, the visitors scored with what was their only effort of the first half.

Kobbie Mainoo released Garnacho down the left and his low cross picked out Mount who steered home for his first goal since scoring in a 1-1 draw here at the Gtech Community Stadium more than 13 months ago.

Brentford equalised in the 27th minute when Michael Kayode slung a long throw into the box and then got above Amass to head it back in after Mainoo cleared. Mikkel Damsgaard’s effort took enough of a deflection off Shaw to creep inside the near post for an own-goal.

Brentford led six minutes later after De Ligt went down on the edge of the box following a challenge with Wissa and the United players appealed for a free kick.

Referee Anthony Taylor disagreed and Christian Norgaard exchanged passes with Kayode before standing up a cross to the back post where Schade rose above Fredricson to plant a downward header into the far corner.

The home side took an even firmer grip on the game with two more goals midway through the second half. Damsgaard fed Mbuemo and he picked out Schade who was ghosting in behind Fredricson to head his second. Then Mbuemo and Mathias Jensen combined so Kayode could square for Wissa to convert.

United reduced the deficit in the 82nd minute when Garnacho unleashed a dipping 20-yard effort past Mark Flekken after cutting in from the left, and again in the fifth of seven minutes’ added time when Diallo did the same from the right before firing through the hapless keeper’s legs.

‘There were a few bits we would like to have avoided at the end, but I thought we were in control from minute one,’ said Frank and he was right.

Amorim, meanwhile, was left to reflect on another European hangover. He says United simply cannot carry on like this. Trouble is, he seems powerless to stop it.