Vincent Kompany is facing a race against time to be fit for the crucial tie against Manchester United this month, reports the Metro.
Kompany hasn't featured for Manchester City since their opening game of the season against Newcastle, where he hobbled off with a groin injury.
The Belgian star was originally ruled out for a month, which gave him hope of returning for the derby against Manchester United on 22nd September.
Now, however, it looks as though City's captain will lose his battle for fitness after suffering a setback during rehabilitation.
Reports are suggesting that there is now no confirmed date pencilled in for Kompany's return, placing doubt over whether he will feature in the side that faces David Moyes' team at the Etihad stadium.
The news that Kompany's return may be further away than expected compounds news that Martin Demichelis, who was bought solely to cover for Kompany's absence, has been ruled out for six weeks with a knee ligament injury.
With Micah Richards still out with injury, and Matija Nastasic only just returning to fitness after a back injury, Manuel Pellegrini could be facing an injury crisis in defence ahead of their clash with rivals Manchester United.
Javi Garcia has been asked to fill in at the back in place of the injured defenders so far, but his ability to defend against United stars Robin van Persie and Danny Welbeck will be questioned after he struggled to handle Cardiff's Fraizer Campbell in a 3-2 loss last month.