Derby came from two goals down to end their barren three-match losing streak with a 2-2 draw in the npower Championship and inflict a further blow on Birmingham's promotion ambitions.
City, who lost their unbeaten home league record to Nottingham Forest last weekend courtesy of a first defeat in 16 matches in all competitions, appeared destined to get back on track.
Just 24 hours after they were slapped with a transfer embargo by the Football League for failing to file their accounts in time, two of five signings made in the last 10 days shone to seemingly put the hosts in a winning position at St Andrew's.
But Derby, winless in six going into the game and without even a goal in their previous four, staged a remarkable comeback thanks to two in five minutes from recalled pair Steven Davies and Theo Robinson.
Substitute Ben Davies produced an inch-perfect cross for namesake Steven to head home and Robinson completed the turnaround, finishing Paul Green's pass from the right as Birmingham were punished for more slack defending.