United started well at Old Trafford and were quick out of the blocks in search of a response to the 3-1 defeat at Arsenal before the international break.
But the optimism of the 74,000 fans in attendance soon drained out of the stadium when Danny Welbeck punched Brighton into the lead on 20 minutes.
Rasmus Hojlund’s disallowed strike before half-time took another hit on morale before Pascal Gross and Joao Pedro added the visitors’ second and third in the second half.
Hannibal Mejbri’s maiden United strike was nothing more than a consolation as Ten Hag’s side suffered their third defeat in five outings.
And it was a deserved beating. Ten Hag set his team up well, switching to a diamond formation with four midfielders, but didn’t react to Roberto De Zerbi’s tactical tweak to shift the game into Brighton’s favour.
United being tactically, technically and physically outclassed by a team that, combined, cost four times less than Jadon Sancho is a significant concern.
Over two weeks ago, Ten Hag revealed that he had excluded Sancho from his squad to face Arsenal due to training performances.
“On his performance in training, we didn’t select him,” Ten Hag explained after the Arsenal defeat.
“You have to reach the level every day at Manchester United. You can make choices in the front line, so in this game, he wasn’t selected.”
Ahead of the Brighton clash, Ten Hag doubled down on his stance, insisting one of his primary aims was to set high standards.
He said: “The club asked me, because there was no good culture before I entered last season, to set some standards. So it’s my job to control the standards.
But the standard of United’s defeat to the Seagulls was far from high. It was an alarming indicator that the club’s progress had plateaued.
Injuries and other factors have ravaged Ten Hag’s options. But United appointed the Dutchman for his tactical nouse, and he was the second-best coach in the dugout at the weekend.
He perhaps needs to remind himself of his own lofty standards to ensure he doesn’t become the fifth casualty of the post-Sir Alex Ferguson era.
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