The Portuguese head coach made the decision to leave Rashford and Garnacho out for the big derby due to their performances in previous games and training.
United won the game 2-1, with Bruno Fernandes and Amad Diallo netting late in the contest.
He told Sky Sports: “We try to evaluate everything training performance, game performances, engagement with teammates, push their teammates up. Everything is on the line when we analyse and try to choose the players. It is my selection. Simple.
“I don’t want to send a message it is simply an evaluation and they know it. The players are really, really smart. Everybody understands my decision and I have to choose. It is simple selection.
“Of course the context is difficult because we have to win games and we have a difficult situation now. I pay attention to everything, the way you eat, the way you put your clothes to go to a game. Everything. I make my evaluation and then I decide.
“There is a communication after the last training. They are alright. They had training this morning and I was there. They trained really well.”
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