Bernardo Silva gave City the lead midway through the first-half before Dino Mavropanos struck with a header minutes later.
Nuno said later: "We had to work very hard and the boys did well, really well.
"The first half was tough because we didn't have much of the ball but at the same time, we controlled, we closed the gaps, we closed the lines, City didn't break us too many times.
"It was positive, the way we reacted to the goal, that we could see immediately we went forward, we achieved a corner and a goal, which against teams like this is important. You cannot put your heads down.
"And again, I think the fans understand it and they suffer alongside us, knowing that the game is hard for us, the quality of the opponent in the end, putting the bodies on the line.
"So, it was a big team effort."
Nuno added, "The result helps us recover because today was a big effort from the boys and it will help us during the week to recover well, in a good mood, enjoying that we are doing things well.
"But we are realising that nothing has changed, our fans know it, we know it, we have to work very hard, very hard, very hard.
"We don't look at the table, we try to ignore it and stay humble, stay humble, stay humble, recognise that it's a long, long way to go."