He was promoted from a B team post to take charge of first-team affairs at Camp Nou and oversaw an era of unprecedented success for the Blaugrana.
Guardiola’s ‘tiki-taka’ philosophy won him a host of admirers, along with three league titles and two Champions League crowns.
Further success was enjoyed at Bundesliga giants Bayern Munich, while a record-breaking Premier League and Carabao Cup double was secured with City in 2017-18.
The 47-year-old is now considered to be one of the finest tactical brains to have ever occupied a dugout, with Premier League rival Nuno among his many admirers.
The Portuguese is set to lock coaching horns with Guardiola at the Etihad Stadium on Monday and believes his opposite number already stands alongside such icons as ex-Ajax boss Rinus Michels and AC Milan great Arrigo Sacchi.
Asked if the City boss is one of the best bosses ever, Nuno said: “Yes, no doubt, but how far back do you go? Rinus Michels? Sacchi? There are a lot.
“When someone brings something new to the game – because everybody knows the game – I think we as managers must develop our ideas to help and develop the game.
“Pep is in that small circle of persons.
“He’s changed his game. By doing that, he was able to change some mentalities of others, whether it be tiki-taka or whatever.”
Nuno added: “He is fantastic He has achieved so many things. His idea of the game is amazing, we all admire that.
“Each manager has his own idea, but [there are] no doubts about it, that we respect each other very much.
“If we can look and see good things that we can use to our advantage, we’ll do so.”
Nuno and his Wolves side took a point off Guardiola and City during a meeting at Molineux back in August.
They will be hoping to repeat the trick when reunited in Manchester, but the reigning Premier League champions are on a run of four successive wins in all competitions and have netted 16 goals across their last two outings in the FA Cup and Carabao Cup.