That is the verdict of Sky Sports pundit and former Liverpool midfielder Jamie Redknapp.
Manchester United were beaten 3-2 at the AMEX on a disappointing afternoon for Jose Mourinho.
Goals from Glenn Murray, Shane Duffy and Pascal Gross put the hosts 3-1 up at the half-time break.
Paul Pogba pulled back a goal from the penalty spot in second-half stoppage time but it was one of few chances the visitors created.
Redknapp was impressed with Brighton, who lost talismanic centre-back Lewis Dunk through injury in the first half.
But he says he cannot remember such a lack of desire from a United team in the past.
“Considering they lost one of their centre-backs as well, when you talk abbot Brighton and how good they are and how well they perform, you always think about the two centre-backs being the stability in the team,” Redknapp said.
“To lose one of them and still carry on was absolutely fantastic.
“They deserve all the congratulations in the world.
“From United’s point of view, having played against them for many years under Sir Alex Ferguson, I always expect a comeback, a bit of desire.
“You can always lose a game, but it’s the manner in which you lose it.
“I don’t think I’ve seen United lose a game like that before in a long, long time, where they showed no desire, no appetite to get back into it.
“They got a penalty which could have been, maybe not, maybe.
“But there was a lack of desire to get back into the game and that is a real worry for Manchester United.”
United will look to bounce back a week on Monday when they host Tottenham.
Spurs have won their first two games of the season against Newcastle and Fulham.