Kenny Miller's ninth goal of the season helped Cardiff extend their unbeaten run in all competitions to 10 matches after they edged out Birmingham 1-0 in the npower Championship.
Miller capitalised on a moment of casual defending by Birmingham centre-back Pablo Ibanez to fire beneath Boaz Myhill after 68 minutes to give the Bluebirds their sixth consecutive home win.
Just five minutes earlier the visiting Blues had been reduced to 10 men following the dismissal of Curtis Davies after he brought down Miller when clean through.
Up until that point Cardiff had been forced to play the majority of the game in front of two lines of Birmingham defence, and both sides struggled to create golden opportunities.
But the red card changed the match in the home side's favour, and Cardiff dominated the majority of the final quarter.
Peter Whittingham hit a post with a rasping free-kick, before firing inches wide from the edge of the box, as the Welsh outfit climbed back into third place.