Goals from United’s former striker Danny Welbeck, familiar foe Pascal Gross and Joao Pedro secured the three points for Albion – who are the Premier League’s top scorers with 15 goals so far this season.
Despite fielding a team worth £17m – with a number of key players missing – Albion outclassed a team full of expensive talent, who are desperately out of form and numerous off-field issues to contend with.
United actually made a confident start to the game, flying out of the blocks but fell behind in the 20th minute. Danny Welbeck played the ball wide to Simon Adingra and ran into the box, with Adingra’s low cross cleverly dummied by Adam Lallana before the United academy graduate struck.
Lively Marcus Rashford saw a shot deflected on to the woodwork as United sought a leveller that they thought had found in the 40th minute. Rashford cut the ball back for full debutant Rasmus Hojlund to steer home what would have been his first for the club – only for the VAR to rule the ball had gone out of play after a long delay.
United looked suspect defensively, with little midfield protection – despite having both Casemiro and Scott McTominay on the pitch.
Gross took advantage of some statuesque defending to dance into the box and double their hosts lead. It was the first time Man United have conceded more than one in four successive league games for the first time since 1979.
The misery was compounded when substitute Joao Pedro made it 3-0, sending dozens of home fans out the exit door. They would have missed a small consolation – when youngster Hannibal Mejbri marked a rare appearance with a superb goal from distance as Albion switched off.
They were unable to mount a miraculous come-back, with a second consecutive defeat leaving them 12th in the table. Here’s how we rated the players:
1. Manchester United 1-3 Brighton
Manchester United’s month went from bad to worse as in-form Brighton continued their recent dominance against the Old Trafford club. Photo: OLI SCARFF/AFP via Getty Images
2. Onana - 5
No chance with Brighton's first two goals. Could have done better with the third, which he got a hand to. Incredible save to deny Ansu Fati a debut goal - one of four stops late on to keep the score down Photo: Ash Donelon
3. Diogo Dalot - 7
Perhaps a surprise to see him start over Aaron Wan Bissaka given the latter's ability to keep Kaoru Mitoma quiet in previous encounters between the sides. Dalot did well in a tough battle against the tricky Japanese forward, though. Some important tackles but not great positioning for third goal, beaten too easily by Tariq Lamptey. Lovely skill to beat Mitoma and played perfect pass to Rashford. Photo: Matthew Peters/Manchester United via Getty Images
4. Victor Lindelof - 4
Poor. Made fans nervous early on when he played a loose ball back to Onana. Couldn’t cope with Albion’s movement in forward areas Photo: OLI SCARFF