Guardiola had feared that his No 1 would not be able to make it after suffering a thigh injury against Atalanta on Wednesday night.
Those concerns were realised after two sets of tests on the muscle problem, with Claudio Bravo now set to deputise in goal.
Bravo was sent off in the Champions League draw in the San Siro, haring from his goal to fell Josip Ilicic – although later insisted that the forward dived.
Guardiola would not put a timescale on Ederson’s absence but launched an impassioned defence of Bravo.
‘Ederson is not available. We have another top keeper,’ the City boss said. ‘Bravo can do it too, we won the Carabao Cup thanks to him, he’s an exceptional goalkeeper, he played a lot of games for Chile.’