United will meet Athletic Bilbao in the semifinals, with qualifying for Europe through the Premier League now beyond them.
"I have to see it," Amorim said of rotating in young players.. "Players like (Diogo) Dalot - they are always ready but today he was really tired. The guys that are recent to have an injury, we will try to save them. We will see tomorrow.
"It's not the best moment or the best season to put some kids to play because again they need a strong base to really show what they can do, but in this moment we need to do it. And sometimes you have surprises.
"Ayden (Heaven) just played - and I can be honest, because we had a lot of injuries in that moment - but today I think of Ayden as my player. So when he's ready, he's facing competition in the team and he's ready to play, so you don't know.
"(Harry) Amass did really well today, so we don't know. Chido (Obi), when he played he played quite well. It's a difficult moment, it's not the right moment for the kids to play, but if we have to do it we will do it.
"Will Obi get more minutes? Yes, I think so. Yes."