The club's new signing has undergone a scan which has revealed knee ligament damage but the Argentina international does not need surgery on the injury
The defender joined the club from Atletico Madrid towards the end of the transfer window on a two-year deal that sees him link up with Manuel Pellegrini who he worked with at Malaga last season.
However, the 32-year-old is set for a spell on the sidelines after Manchester City confirmed he had undergone a scan which showed he had suffered knee ligament damage, although he will not need surgery to rectify the problem.
Demichelis's injury leaves Pellegrini with selection problems in defence, as captain Vincent Kompany is currently side-lined with a groin injury while Micah Richards has a hamstring problem and Matija Nastasic is only just back in action after an ankle problem.
City's defensive woes have seen them forced to use Javi Garcia in defence this season alongside Joleon Lescott, during the club's shock 3-2 defeat at Cardiff.