The Championship clash at the City Ground burst into life in the final quarter as Blues found themselves two goals to the good in the space of as many minutes thanks to Marlon King and Hayden Mullins.
Both managers agreed that the visitors had worked effectively to contain Forest's attacking threat.
Sean O'Driscoll: "I didn't think we deserved to be 2-0 down but you have to give credit to Birmingham. They came with a game plan."
Lee Clark: "We knew what Forest were all about but we stopped them playing and they were not cutting us open as they can."
Simon Cox came off the bench to great effect as he gave the home side hope and Dan Harding completed the comeback with a goal that was official given to Birmingham defender Pablo Ibanez.
O'Driscoll: The three substitutes did very well but if you are going to do well in this division you need 16, 17 or 18 players."
Clark: "The players were excellent but we were guilty of dropping too deep, giving the initiative to the Forest lads.and they took it."