United dominated the game, but lost 1-0 thanks to Riccardo Calafiori's scrambled first-half header.
Amorim reflected afterwards: "We were more aggressive than last year. We sprint more. We were more brave. We let one against one all the game. We pressed high. And then with the ball, we have quality. Even when the stadium makes some sounds, we continue to play the way we play.
"We lost fewer balls in the build-up, compared to last year, was (where) we struggled a lot. And then the small things that we talk about in the beginning of this season, that players like (Matheus) Cunha, like Bryan (Mbeumo), in one moment can elevate the stadium. So, I think the most important thing, we were not boring.”
Amorim also insists goalkeeper Altay Bayindir was fouled in the scramble for Arsenal's winner.
He stated: "More or less the same that happened sometimes last year. For me, it's not playing the ball, it's protecting the guys that they are attacking. I understand that we want goals, but when you're touching the goalkeeper in that way, I think it's hard.
"And especially to lose with a goal like this, I think it's hard. It's hard to be strong when you have to push and to go for the ball. Sometimes you are pushing and then you don't have more hands to go for the ball.
"We need to be stronger in that moment, but, especially, we need to do the same thing in the opposite side. So, we are not changing the rules. We have to adapt to the rules."