Birmingham striker James McFadden scored an injury-time penalty to stun leaders Arsenal and rescue a point at St Andrews.
Two second-half strikes from Theo Walcott (50 and 55) looked to have enabled Arsenal to overcome a sickening leg injury to striker Eduardo after just three minutes for which Martin Taylor was red-carded in the second minute.
But McFadden, who had given Blues a half-time lead with a fine free-kick in the 28th minute, levelled from the spot after Gael Clichy was adjudged to have brought down Stuart Parnaby deep into added time.
Arsenal had only themselves to blame for not collecting all three points with only some excellent saves from Blues keeper Maik Taylor and an off day in front of goal by Emmanuel Adebayor prevented Arsene Wenger's side taking victory.