The Argentinian has already been ruled out of Monday’s game with Wolves after failing to take part in full training since breaking down in June.
Pep Guardiola claims the 32-year-old is taking time to get back to top condition and will need longer before he will be ready to lead City’s attack.
City’s manager said: “We knew that the injury was difficult. He is doing the job, in maybe one month or two months he will be ready.
“Still he hasn’t had one training session with us.
“He has to come back on the pitch and regain the physical condition.
"Sergio was out for a long time and Sergio is not a guy who regains the physical condition quick, so I think in one month or two months he will be ready.”
Guardiola had hoped Aguero would be able to take part in the Champions League closing stages last month, but his recovery has taken longer than club medics expected.
It means Gabriel Jesus is set to lead City’s attack as Guardiola’s only like-for-like back up.
Riyad Mahrez has been back in training this week after testing positive for Covid-19, but Aymeric Laporte, who also tested positive, is out of the Wolves game.