Manchester United boss Erik ten Hag says his young players will learn from their preseason defeat to Wrexham in California.
Elliot Lee and Aaron Hayden had the League Two side 2-0 ahead in the first half, before United wing-back Marc Jurado struck before the break.
United attacker Dan Gore then saw red before Sam Dalby added a third for the Welsh.
"We're disappointed with ourselves," Ten Hag told MUTV at full-time.
The way we played in the first half was a little bit erratic to the structure.
We had some other objective that it was not [just] the result, but with young players we have to learn from it and I'm sure they will do.
This is what happens in top football. It definitely is [physical] in the Premier League, so our players have to get used to it.
You don't face this is in youth football; this is men's football and it is really good that they have this experience. It's negative but you learn from it.
It's a learning moment and as Manchester United players, you have to deal with it.
With the pressure from the crowd, it is good that we have this. You have to learn to take that and we will carry on."