Manchester City midfielder David Silva could be out of action for as long as a month after picking up a calf strain.

The Spaniard played 66 minutes of City's 5-2 Champions League win at home to CSKA Moscow on Tuesday night but is now facing a spell on the sidelines.

"I don't know how many weeks at the moment, but it could be three or four," confirmed City manager Manuel Pellegrini.

Pellegrini is currently without skipper Vincent Kompany and there are doubts over the availability of Fernandinho and Matija Nastasic for the game at Sunderland on Sunday.

"It (the Kompany injury) was diagnosed as being a five-week problem," said Pellegrini. "That was three weeks ago, so he should be fine in another two weeks.