City face an anxious wait to see how long they will be without Aguero, who limped off with a hamstring injury after scoring the third goal against Stoke.
The Argentina striker is expected to miss the FA Cup tie at home to Watford this weekend and the trip to Arsenal in the league on January 13. But City first team coach David Platt suggested that his lay-off may be even longer.
Platt said: "It's difficult to assess an injury like that for how long it's going to be.
"There are different degrees of hamstring, that's why you need the 48 hours. There will be swelling and bleeding so you need to give it time. It's a blow, but when you have so many games in a short space of time you run the risk of this."