Aguero was on the bench against the Potters but didn’t come on as he recovers from a rib injury.
Guardiola said: “Day by day he is much better, yesterday (Sunday) he made an amazing training session.
“The day before Stoke was good but not perfect - yesterday was really good.”
City are in scintillating form at the moment but so are Napoli, with Maurizio Sarri’s side flawless in Serie A so far this season.
The Stadio San Paolo side have played eight and won eight in their domestic league, boasting a goal difference of plus 21.
It all makes for an intriguing encounter at the Etihad Stadium, and Guardiola added: “I’m pretty sure it will be fascinating, hopefully our fans can come to help us.
“Napoli do many things, and all the things they do they do perfect.
“They are not a team that will wait, they will push forward and can build from the middle, or outside.”
