The Finland international striker's brace at Glanford Road, his first goals of the season at club level, helped Blues progress to the Third Round of the Carling Cup on Tuesday night.
"We always knew it was only a matter of time before Mikael started scoring goals again," Bruce said after the game.
"I would have liked to have rested him for a little longer because we are still trying to nurse him back after his knee operation..
"If Emile [Heskey] hadn't been injured he probably wouldn't have played as many games."