Wanderers stunned Pep Guardiola's then-reigning Premier League champions with a shock 2-0 win at the Etihad Stadium last October before backing it up with a sensational 3-2 comeback success just after Christmas.
City begin their quest to regain the title from Liverpool at Molineux on Monday evening.
Nuno has proved he can outmanoeuvre Guardiola but is adamant previous results count for little.
"Games are never the same. What we look at it is the quality and the way Man City play the game: talent, speed of the ball, all of these things we have to look for and pay attention to," said Nuno.
"At the same time, looking to build on our idea, looking to play our game and do things well.
"But things will never be the same. This is what we have to realise. It's a new game and a new challenge ahead of us.
"You know the talent and the quality of Man City's squad, it's amazing the quality of their players, their manager, Pep, all this.
"It's going to be hard, it's going to be very difficult. We expect a very, very tough match and we want to compete against a fantastic team."
Having narrowly missing out on Europa League qualification last term, Wolves kicked off the new campaign with a 2-0 success away to Sheffield United.
City are yet to return to action and undoubtedly have a point to prove after Jurgen Klopp's Reds stormed to the title with a resounding 18-point margin.
Nuno is unsure whether his forthcoming opponents will be able make up that sizeable gap in the 2020-21 campaign.
"I have no idea what will happen," said the Portuguese.
"After such a quick turnaround it's unpredictable to guess what is going to happen. Nobody knows.
"We are focused on ourselves, knowing that the Premier League is really, really tough and will demand a lot from us."
Wolves have been on an upward trajectory since promotion from the Championship in 2017.
Nuno remains optimistic the club can continue to progress.
"I am confident that we will. But it's not about what we did before," he said.
"These three seasons we created an identity, we created a way of how we play and how we operate as a group, and we have to maintain these high standards that we have because a new challenge and a new cycle is ahead of us.
"Things will be much more difficult than before because all the teams are improving and we have to follow up and keep on going."