For the first time in the Premier League era United have lost three of their opening five games and face a daunting task to open their Champions League campaign away to Bayern Munich on Wednesday.
Ten Hag had been sheltered from criticism in the early weeks of the campaign as supporters concentrated their anger towards a series of off-field issues.
Despite the fans' desire to see them gone, the Glazer family appear to have put a process to sell the club on hold.
Brazilian winger Antony (23) has been given a leave of absence to fight domestic abuse allegations made by his ex-girlfriend.
Meanwhile, United decided Mason Greenwood (21) had no future at Old Trafford last month despite abuse charges against him being dropped.
Ten Hag was credited for returning United to the Champions League by finishing third in the Premier League last season and ending the club's six-year trophy drought by winning the League Cup.
However, he was the target for a chorus of boos when he substituted new signing Rasmus Hojlund (20) midway through the second half of Saturday's 3-1 home defeat to Brighton.
The Dutch coach tried to spin that moment into a positive show of support for Hojlund, who was making his home debut after a £64 million move from Atalanta.
The Dane has only recently returned to fitness and Ten Hag could ill afford to lose another key player by forcing him to play 90 minutes too soon.
But United's bet on the 20-year coming good in the long run could face a backlash should they be undone by Harry Kane (30) in Germany.
Despite their need for a striker, United never tested Tottenham's resolve for the England captain, who instead joined Bayern in a €100 million (£86 million) deal.
Kane has hit the ground running with four goals in as many starts, while Hojlund is yet to find the net for United.
Sancho disciplined
To add to United's woes going forward, winger Jadon Sancho (23) is also absent from first-team action due to a spat with his manager.
Sancho, who cost £73 million from Borussia Dortmund just two years ago, has been ordered to train on his own after claiming he was a "scapegoat" when Ten Hag criticised his poor performances in training.
Ten Hag's disciplinarian streak was heralded as part of his success in his first season as even Cristiano Ronaldo (38) and Marcus Rashford (25) were not afforded special treatment.
The United boss is yet to face much fan fury for his latest stance as Sancho has failed to live up to his price tag.
But that decision has upped the pressure on Ten Hag to lift the mood around the club with an upturn in results on the pitch.
With United already trailing local rivals Manchester City by nine points in the Premier League, making an impact on the Champions League is even more vital to the success or failure of Ten Hag's second season.
"It's about character," said Ten Hag, ahead of his return to Munich, where he coached the Bayern B team between 2013 and 2015.
"Now we have to see how strong we are, how the team sticks together and which players are standing up and showing the character and leading the team."
