The Old Trafford giants are in the midst of their latest post-Sir Alex Ferguson rebuild after a wretched campaign that saw Ole Gunnar Solskjaer sacked and interim replacement Ralf Rangnick flounder.
United’s poor season means they are currently preparing for Europa League action rather than Champions League football, with the side jetting off to Cyprus to face Omonia Nicosia reeling from a humiliating 6-3 derby defeat.
Erling Haaland and Phil Foden both scored hat-tricks in a hammering that showed the chasm between Ten Hag’s side and back-to-back Premier League champions City.
“Obviously it was a difficult day,” Ten Hag said. “As always we analyse and we do that tough, the reality. It was a reality check, so we have to learn from it and carry on. You always take respect of the opponent but we will still stick to our philosophy, our rules, our principles.
“In tactics sometimes, also to surprise opponents, you have to bring something different in your game, and we will do that also for the future. But we can get a lot of confidence about this theory, when you beat Arsenal, you beat Liverpool and now we get a reality check with Man City – so we know we have to step up.
“So thank you for the lesson, from Pep and City. We will take that and we have to understand we have to do things much better.”
Ten Hag always knew there would be setbacks along with positive results but said Sunday’s performance was “unacceptable”.