Regulars of this column will know we're fans of the Dutchman. For this United job, at this time in their history, Ten Hag is the right man to lead the club forward. But he's messed up and, as early as mid-November, it could break United's season.
Everton away - a galvanised (they're all throwing that word around) Everton and a heaving Goodison Park after Friday's points penalty. That's what United's players face once they reassemble after international week.
And then, three days later, it's 'Welcome (or is that Return?) to Hell' time: Rams Park and Galatasaray in the Champions League. In terms of weeks, you'd be hard-pressed to find a tougher one for any player of Manchester United from any generation.
And making it worse, they could be forced to do it with a rookie goalkeeper. News coming from Cameroon is that Andre Onana (27) is now touch-and-go. A late match injury against Mauritius forced United's number one to call for his own substitution on international duty. And while there is confidence the setback isn't serious, there remains confusion over the extent of the adductor injury. But either way, Onana's decision to end his international exile and return to Cameroon hasn't gone to plan.
So for the moment, he's out. Onana is out of the World Cup qualifier against Libya on Tuesday. And if he's not fit for that tie, then there have to be doubts about him making the trip to Goodison and even Istanbul.
So Ten Hag is left with his young Turk. Of course, Altay Bayindir (25) is no rookie. Indeed, he has everything to be an outright Premier League number one. But he's not managed an appearance for United since his deadline-day arrival - not for the first team nor for the U21s. And even for last week's friendly against Hull, he was missing due to international duty with Turkey.
Describing Bayindir as underdone would be an understatement - particularly for what lies ahead for him and his back four next week.
So as we say, Ten Hag has been caught out. Poor management? Poor planning? Yes. It must be said, he's messed up.
The only bonus is that Bayindir will know exactly what to expect next week at Rams Park. But the entire situation smacks of 'it'll be alright on the night,' which really isn't good enough for a club of United's status.
Of course, flip it and it could be a story for the ages. No games, no preparation, and this lad of 25 defies the odds. Imagine he keeps a clean sheet at the Gwladys Street End on Sunday and then does the same against Gala on Wednesday. Certainly, the belief inside United is that Bayindir is capable of pulling off such a performance.
As much as a deadline deal suggests a panic buy, United's football chiefs had long pursued Bayindir. There was an expectation that he would actually sign a pre-contract as a Bosman towards the end of last season. But despite holding talks with United, Bayindir penned a new deal with Fenerbahce on the guarantee from President Ali Koc that he would be sold if United came in with a reasonable offer.
"After January, Altay became a player who could make a free transfer," Koc said after Bayindir's departure.
"Naturally, offers came. The path was completely open for him to move on to another club without any hesitation.
"A very big offer came from Manchester United, but since he was a free agent, it was nothing that Fenerbahce could get involved in.
"Yet, Altay extended his contract with Fenerbahce without any obligation. He wanted to help his club make money..."
Again, this is football and anything can happen. Legends can be made. And should Onana not make it, Bayindir will see this as an opportunity. An opportunity to make his name and to make an instant impact.
For long-time United fans, they'll recall the 1990 FA Cup final and Alex Ferguson's axing of Jim Leighton for his little-known reserve keeper Les Sealey for the replay. Sealey would not only keep a clean sheet and win the Cup, but he'd also keep his place the following season and win the Cup Winners' Cup final against Johan Cruyff's Barcelona.
This is what football offers - it's an opportunity, especially at a club like United. And it's not beyond Bayindir to emulate what Sealey did all those years ago. But it must be said, his manager has done him no favours in the lead-up.
