Former United winger Anthony Elanga struck for the 1-0 win at the City Ground.
Nuno said afterwards: "Over the moon. We are delighted, realising how the game went. We could not be more proud than we are, because it was very tough."
Nuno also hailed Elanga for his winner, with the winger running 85m in nine seconds before scoring.
He continued: “Amazing. With the ball; so imagine (how quick) without the ball!
“He did it by himself. Credit to him. He has this special ability to drive with pace and still control the ball at such a huge speed. The finishing was great.
“It was very special. He has this ability of driving. It is the capacity to drive with the ball with pace and still be able to control it. To do that is very difficult and requires a lot of technique.
“From all of our players, I think. It doesn’t matter the age, as long as there is commitment and dedication I think we can improve all of them.”
Nuno was also eager to highlight Murillo after his last-minute block to deny Harry Maguire from scoring an equaliser for United.
He said: "It was huge for us. Better than a goal, wasn’t it?
“The fans played their part. We were against the ropes. In this moment, we were against the ropes, and it was about heart and belief because the legs weren’t there anymore.
“I'm very proud of them. Very, very proud of them.
“Today it was Murillo, but we have had others (make big clearances). When you don't have energy, you have to have belief. Belief is what can I do to stop the ball going in the net? It is a good example of the dedication and the commitment of the players.”