The Spaniard was replaced by Aleksandar Kolarov on 66 minutes during the Premier League giants' 5-2 Champions League win over CSKA Moscow on Tuesday
Manuel Pellegrini is sweating on the fitness of David Silva after the Spaniard picked up a calf injury during Manchester City's 5-2 victory over CSKA Moscow.
Silva has cancelled a scheduled appearance at an event in London's ExCeL Centre on Wednesday afternoon to undergo tests on the problem.
The Spaniard attempted to play on against CSKA after sustaining the knock, but eventually succumbed to an injury which has troubled him in the past and was replaced by Aleksandar Kolarov on 66 minutes.
But despite his fitness concerns, City staff remain optimistic Silva will be fit enough to face Sunderland in the Premier League on Sunday.