The Erik ten Hag era at Manchester United began with a 2-1 Premier League defeat at home to Brighton & Hove Albion as the Dutch manager was shown just how much work is ahead of him.
There were yet more loud and angry protests against United's owners, the American Glazer family, before the kick-off and it was also a familiar scene on the field.
Brighton took the lead on the half-hour with Leandro Trossard finding former United forward Danny Welbeck who squared the ball to the back post for Pascal Gross to slot home.
Nine minutes later, Gross doubled the lead, with his sixth career goal against United, after David De Gea had poorly pushed out a Solly March drive right into the path of the German who again made no mistake.
Ten Hag introduced Cristiano Ronaldo in the 53rd minute and the Portugal forward, who is reported to want to leave the club, provided the spark for United's attempted comeback.
The home side gave themselves a foothold in the 68th minute when a goalmouth scramble ended with Alexis Mac Allister turning the ball into his own net but Brighton held on for a second straight win against United, following their 4-0 victory in May.
Meanwhile, new Manchester City signing Erling Haaland marked his Premier League debut with a double as the champions began their title defence with a clinical 2-0 victory over West Ham United at the London Stadium.
Pep Guardiola's City were awarded a penalty after 36 minutes when Haaland charged past the West Ham defence to latch onto a through ball and take it around Alphonse Areola before being fouled by the substitute goalkeeper.
The Norwegian striker stepped up to convert the spot kick, his cool finish sending Areola the wrong way to give City a deserved lead after an utterly dominant first half in which West Ham were rarely able to venture from their own box.
City midfielder Kevin De Bruyne then defended a series of crosses before slipping through a delightful pin-point pass to Haaland, who timed his run to perfection and slotted home with a fine left-footed finish in the 65th minute.
West Ham forward Michail Antonio had headed wide in the opening stages and De Bruyne easily cleared Jarrod Bowen's free-kick just before halftime, but the hosts struggled to make their mark on the game in a largely toothless attacking display.
Manager David Moyes brought on Said Benrahma and new signing Gianluca Scamacca just before the hour mark in an attempt to change West Ham's fortunes but Haaland doubled City's lead minutes after and the visitors comfortably saw out the win.
Reuters
