United won 2-1 with Harry Maguire nodding a winner in injury-time.
Amorim said afterwards, "We had to believe until the end but this game has nothing to do with the time of Fergie. I think the performance, we have to do so much better with the ball, without the ball.
"We didn't have any energy in the beginning, especially in the first-half. Then in the second half we played a little bit better, with a little more speed, winning second balls. Then we managed to turn things around so it was a good result not a good performance.
"The coach is the first responsible, when one team doesn't perform, doesn't improve, it is the coach but we are here to do things and to see the game, to study the game and try to improve for the next game.
"I think it's the small things, if you see the games sometimes it's to control the ball, to have the ball, don't give the ball away in the first pressure. It's the small things, it's the big things, it's everything.
"It's this moment, it's hard away but especially at home but we have to cope with that and we will try to do it next game."