City were dominant through at the Etihad with the game wrapped up inside their first half thanks to a brace from Bernardo Silva and Phil Foden’s brilliant strike.
Silva has found himself on the edge of Guardiola’s plans so far this season but the Portuguese star crashed home a fine opener.
Birmingham never really recover form that setback as Silva quickly made it 2-0 before fans favourite Foden bulleted home a third.
And it was all one-way traffic again after the break as Silva was expertly denied a hat trick by visiting keeper Andre Prieto.
Birmingham did almost nick a consolation late on as winger Jeremie Bela tested Zak Steffen but it wasn’t to be on a straightforward afternoon for City.
Full Time at the Etihad Stadium it’s Manchester City 3 Birmingham City 0