The Hammers will host United having won at Burnley on Saturday.
Nuno said ahead of tonight's clash: "I think they’re playing very well, and they’re in a good moment. You can see that their players are confident, and we know it’s going to be tough because they have a lot of talent.
"It’s going to be totally different to the last time we played them. It’s a new game, and new things will happen. I think Manchester United have shown they have changed, and right now they are playing really well.
"We’ve looked at many things that they do, and Bruno Fernandes is someone we have to look at. He’s a fantastic player, and I have a lot of admiration for Bruno.
"The fans have been amazing. They have been very supportive, and they were brilliant at Burnley. We need this energy again tomorrow, because we need them.
"We know it’s up to us. The moment that we give to our fans, they will give back to us.
"I believe we are ready to compete against a very good team, so let’s go."