United host Pep Guardiola’s team on Saturday but rather than using his first Manchester derby to motivate his players, Ten Hag will tell them to show the bravery to play, but without being naïve.
Erling Haaland and Phil Foden scored hat-tricks in the match at the Etihad Stadium, when United were 6-1 down before a late double by Anthony Martial.
But Ten Hag said: “It is not about that game any more. That is the past, it is about the future, You can’t change the past but you can change the future.
“It was a lesson and we took that lesson and from that point on we make huge progress so we have to continue the progress. That game was a setback. We can all find reasons why but always you have to act, to deliver.
“As a manager, you have to go to certain steps, you need a clear philosophy a clear point where you want to go, a direction, and then it is about development. That is what we did but like many things in life particularly football there is never an end point.”
Ten Hag will urge his team to focus on themselves, rather than worrying about City. He explained: “The opponent plays an important role in football but you have to play your best game.
“That is what I demand of my players, play your best game with full belief, not be naïve, and act like a winner. It is about the mental approach and attitude so we have to be brave, act with belief and play our game.”