Chris Wood struck for Forest, with Fulham winning via goals from Emile Smith Rowe and Calvin Bassey.
Nuno said, “We have to look at the game. We have to know that the change gave us more width and more things we are used to.
“But at the same time, the contacts in the box from the crosses were not there. We were rushing a little bit.
“There are so many things I would do differently now. Now it is about looking at the game and preparing for the next one.
“The idea of the formation was to have an extra body and try to control things better. What we anticipated, and what was the reality, was that Fulham’s strength is having good players in wide areas. And then they occupy the box well.
“The idea of having an extra body to control that situation didn’t happen. Unfortunately it didn’t work out.
“It was a tough game. First half, Fulham caused us a lot of problems and were in control of the game.
“We were able to get back in the game with Chris’ goal, which he made by himself. We started the second half well but then we started losing duels and allowed Fulham too many set-pieces, which caused us problems.”