Nathan Ake was forced off during the same match as Akanji, being withdrawn in the final few minutes of the victory over Forest.
The Dutchman is believed to have sustained a thigh issue but details about the injury are pretty thin on the ground.
The only thing that Guardiola was prepared to say about Ake is that he will be out “longer” than Akanji.
With that being the case, it would be a surprise to see him back against Aston Villa this weekend, having already missed the last three matches like his teammate.