A David Davis header followed by a Clayton Donaldson brace saw Blues run out comprehensive winners against the previously unbeaten Norwich City at St. Andrew's.
The game got off to a bright start with both sides going close within the first three minutes. First Jacques Maghoma cut inside from the left and rifled a shot inches wide of the post before the visitors saw a goal ruled out for offside after Jonny Howson poked a loose ball past Tomasz Kuszczak.
Blues deservedly took the lead after 22 minutes courtesy of a powerful header from David Davis. Steven Whittaker fouled Maghoma, who was a constant threat down the left, but after the referee played advantage the winger got to his feet, sent a beautiful curling ball into the Norwich area and in charged Davis to head past Michael McGovern.
The Canaries offered little in attack after that, a tame strike from Jacob Murphy the only effort of note in the remaining minutes of the first-half.
In fact it was Blues who almost found another goal before the break when a free-kick from Maghoma whistled just over the crossbar from 25 yards.
Norwich came out with greater purpose in the second-half but again it was Blues who created the better chances. Che Adams spurned a great opportunity to get his second goal in as many games when he rounded the keeper, unfortunately he could only find the side netting. Moments later the unmarked Robert Tesche somehow found the underside of the crossbar rather than the back of the net from six yards after Clayton Donaldson had found the German with the goal gaping.
But with just over 20 minutes to play the hosts finally got the reward that their performance deserved. It came from the penalty spot after Donaldson was bundled over by Whittaker inside the penalty area and the Blues striker collected himself to cooly finish for his first goal of the season.
Donaldson then put the finish on a fantastic Blues performance when he capitalised on a poor pass back from Alex Tettey before poking the ball past McGovern in front of a buoyant Tilton Road.