Manchester City were forced to settle for a second goalless draw on home soil in four days as they failed to break down Birmingham's defensive barrier.
James Milner came closest to breaking the deadlock when his shot was booted off the line by Stephen Carr 15 seconds from the restart.
But the City supporters were not impressed, and vented their frustration at manager Roberto Mancini when he replaced crowd favourite Carlos Tevez with Gareth Barry in the latter stages.
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