Arsenal boss Mikel Arteta says there's lessons to be heeded from their preseason defeat to Manchester United in New Jersey.
United won 2-0 thanks to goals from Bruno Fernandes and Jadon Sancho.
Arteta said: "Having a tough match of this level in this context gives you a lot of information, and that's always very positive. That information is obviously there are a lot of things we have to improve. How important the boxes are, that errors are part of football, you have to overcome them as well. And how painful it is to lose a game. Physically it's been super, super demanding. Some players we want to expose a little bit more than they have done, because the way we want to build them, their physical state.
"Overall they had their moments when they were so efficient. We had ours, when we had more dominance and we certainly tried again in the second half, but the chances we had, we didn't convert them, and they won the game.
"Yes (it was a good lesson), you asked me yesterday about my thoughts on how difficult or easy the season is going to be. It's going to be more challenging, more difficult, the level and preparation of the team is excellent and we knew today, they had already played two games before this one and we knew the test was going to be really demanding, like it's going to be on Wednesday against one of the best teams in the world."
On what he learnt from the game, Arteta also said: "That I hate to lose and we all hate to lose. That is the biggest lesson, that I don't like losing and I don't like the feeling that I have right now. So the boys have to train right now, in that space thinking how we are going to be better to win the next match."