Speaking in his latest press conference, the Portuguese head coach confirmed that despite the need to win on Thursday night to avoid a two-legged play-off next month he will be rotating his side to avoid fitness issues.
"We have to rotate some players," he said. "Everybody is prepared - and it is crucial for us to stay in the top eight and to avoid the play-offs.
"Like I've said so many times, we need time to train. We need to rest some players also, so we need to win tomorrow.
"We have to face the game in a good way, fight for every ball, but to improve with the possession and we'll try, tomorrow, with the starting XI, to have players with a lot of possession, to control the game, because it's really important, especially in the beginning."
Amorim confirmed the 21-man travelling squad ahead of the flight to Bucharest which did not include Marcus Rashford. Luke Shaw, Mason Mount, and Jonny Evans are also unavailable for a clash that could push United up to second place in the Europa League table if they can secure 3 points.