The Red Devils are set to take on Arsenal in the Premier League away from home on Wednesday.
Amorim, whose team drew with Ipswich and beat Everton, will now have to face a much higher caliber team.
Amorim stated as much, telling reporters: "Yeah, it’s the best team. It’s the best team that we’ve faced, by far. But the test is every game. If you see the last game, yesterday, was really tough. It was a 4-0 but you see the game like I see it. Every game now is a test without so many minutes to train.
“Trying to manage the numbers of minutes of so many players, you cannot try to imagine one game. You have to know that some players might have to be out of the pitch in 60 minutes, 70 minutes so it’s really hard at this moment.
“Everything is a test but Arsenal are… I know it’s not easy for (a) Manchester United (head coach) to say, but they are in a different point of their team. They are in a different moment."
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