Nunes impressed in the role for Sunday's 0-0 draw at Manchester United.
“He can become a good right-back for the physicality he has,” said Guardiola. “The thing is not to play in the middle because he’s not clever enough with the composure.
“He is learning a lot. The full-backs make a mistake when they cross for the far post and they are sleeping.
“But he defended two or three crosses that Bruno Fernandes put into the far post for Dorgu.
“He has the physicality to do it. He can play there, and he helped us a lot.
“When he started the season if you said we play Matheus at right-back and Nico O’Reilly at left-back, I would say what are you talking about?
“But the season is what it is.
“Akanji is coming back, and we have two young central defenders.
“But the last two or three games, the back four today again was excellent.
“Today Ruben was incredible. Josko as well. Nico, the last 20 minutes he was tired. It’s new for him but he played really, really good.
“We build from that.”