The midfielder, who was making a return from injury, reacted quickest to a rebound to score.
For United, the result saw them drop to 15th place in the Premier League table, two places above the relegation zone.
Speaking to Sky Sports after the game, Amorim bemoaned his side’s inability to put the ball in the back of the net.
He said, “In the end, they scored; we didn’t. That was the big difference in the game.
“We had a lot of chances, but in the end, they scored one and we didn’t.
“The first step is to create chances. We have had games where we were around the box but didn’t create chances. In this game, we created chances.
“But in a match between two teams not doing well, one goal was always going to make the difference.”
Written By Ifreke Inyang