Brilliant Brighton secured a famous 3-1 win at Manchester United as things went from bad to worse for Erik ten Hag’s side after a challenging fortnight.
Brighton heaped further misery on United as attention returned to on-field matters on Saturday afternoon, with Danny Welbeck, Pascal Gross and Joao Pedro scoring before Hannibal Mejbri’s consolation effort.
The comprehensive end of the Red Devils’ 31-game unbeaten home run in all competitions came against the side that last beat them in the league at Old Trafford in Ten Hag’s first match in charge.
Welbeck opened the scoring against his former club, before a Marcus Rashford strike hit the woodwork and Rasmus Hojlund’s first goal for the club was ruled out by the VAR.
Gross netted both goals in last season’s Old Trafford win and fired Roberto De Zerbi’s men further ahead early in the second half, before substitute Pedro landed another body blow.
Boos greeted Ten Hag’s decision to bring Anthony Martial on for full debutant Hojlund, but fellow introduction Hannibal did his bit when striking home his first for the club from distance.
But there was to be no stirring comeback like in United’s last home game against Nottingham Forest as attention now turns to Wednesday’s Champions League clash at Bayern Munich.
Brighton have a historic Europa League match against AEK Athens to look forward to themselves after winning at Old Trafford for just the second time in their history.
Rashford’s skill and perseverance ended with a low drive being saved by Jason Steele and Hojlund headed over, before nearly combining when the new boy stretched for the home-grown star’s cross.
But De Zerbi’s side looked unruffled and took a 20th-minute lead at the end of a well-worked move.
Welbeck burst towards the box having played wide to Simon Adingra, whose low ball from the right was smartly left by Adam Lallana for the 32-year-old to smash home.
De Zerbi surprisingly made six changes on Saturday, when Ten Hag made three and plumped for a midfield diamond that caused the visitors early problems
The opener gave Brighton fans an extra pep in the step and the goalscorer tried his luck from distance, with United offering little in response until the 34th minute.
Casemiro swept the ball out to Rashford on the left, with the forward darting inside and getting away a drive that Joel Veltman turned on to the woodwork with an unorthodox block.
United bounced back from that near miss and celebrated an equaliser five minutes before the break.
Rashford followed stepovers by darting to the byline and pulling back for Hojlund, who turned and prodded in what appeared to be his first United goal.
But with play ready to resume at 1-1, referee Jarred Gillett was informed by VAR Chris Kavanagh that the ball had gone out of play before Rashford could get the pass away.
The England international continued to look dangerous and went close in first-half stoppage time, then struck into the side-netting when the second half got under way.
But Brighton were still pursuing a second and their warning shots across the bows went unheeded.
Gross ran on to a pass by Tariq Lamptey just inside the box, sent Lisandro Martinez flying with a drop of the shoulder and fizzed past Andre Onana in front of the away fans.
The 53rd-minute effort left United reeling and Ten Hag turned to his bench, but the decision to replace Hojlund with Martial was audibly unpopular.
Rashford saw a free-kick stopped as the hosts desperately looked to claw a goal back, only to be hit by a Brighton third in the 71st minute.
Lamptey raced down the left and cut back for substitute Pedro, who opened his body to hit a first-time, right-footed shot that Onana could not stop finding the net.
Punch-drunk United managed to pull one back immediately through youngster Hannibal, who lasered an effort past Steele from 25 yards two minutes later.
Victor Lindelof headed over but intelligent Brighton were able to take the sting out of proceedings, exposing gaps left by the desperate hosts.
Kaoru Mitoma, substitute Evan Ferguson and debutant Ansu Fati saw shots saved as the clock wound down. Onana stopped the latter again in stoppage time.
Gross said after the game: "We played a good game, we controlled it really well and deserved to win.
"We needed to organise ourselves a little bit at the start as they played a different shape. But after we figured it out we were better defensively and were in control on the ball, found spaces and were dangerous on the attack."
On working with manager De Zerbi he said: "We all enjoy it. We are really hungry, he is really hungry, everyone tries to get better as a team. We are really lucky to have him and we keep going.”
Manchester United midfielder Eriksen said of the defeat: "It is a heavy one. We have to look at ourselves. We changed some things but we are disappointed.
"In the first half we had a lot of moments, had good control. They had a lot of possession but not many chances. They then score with their first chance and the system they play they keep the ball a lot and we had to chase it down. But we still had chances to get back into the game."
On what needs to be done to turn things around, he said: "The small things. We had the offside at Arsenal and today when we scored but it was out of play. The small things we are missing and a bit of luck to get over the line and get something out of the effort we put in.
"Any game at the start of the season, doesn't matter who you play, is very important. We focus on our games and whoever we play we want to win. But we have lost three already and we have to change that."