Kevin Phillips grabbed his fourth goal of the season as Birmingham beat QPR to move top of the Championship.
The first half had lacked any serious goal threat until Phillips prodded in from close range just before the break.
QPR failed to muster any signs of being able to get an equaliser as the Blues defence comfortably held them at bay.
Birmingham were not at their best but the lack of ideas and urgency from QPR rarely troubled them as they secured a seventh win in 10 league games.
Birmingham manager Alex McLeish:
"It wasn't a fantastic performance but it was a sleeves rolled up type of game.
"The timing of Kevin Phillips' goal just before half-time was absolutely brilliant.
"The first 20 minutes was not very pretty when we didn't retain the ball. As the game progressed I was much happier with our possession.
"For some reason I had a lot of faith in my players in this game and I was very happy with the outcome."
QPR boss Iain Dowie:
"We are not firing off enough cylinders but saying that it could be a very different picture with a couple of good results against Swansea and Nottingham Forest.
"The character is in the side. I have no problem. I'm disappointed with the points return in the last four games but that is what this league is all about.
"I was happy with the first half but not the second half."
Birmingham: Maik Taylor, Parnaby, Jaidi, Ridgewell, Murphy, Larsson, Carsley (Nafti 50), Agustien, Owusu-Abeyie (McFadden 75), Phillips (Jerome 80), O'Connor.
Subs Not Used: Doyle, Martin Taylor.
Booked: Ridgewell.
Goals: Phillips 45.
QPR: Cerny, Ramage (Connolly 87), Hall, Stewart, Delaney, Rowlands (Ledesma 80), Leigertwood, Mahon (Buzsaky 68), Cook, Blackstock, Agyemang. Subs Not Used: Camp, Parejo.
Booked: Leigertwood.
Att: 18,498.
Ref: Andy D'Urso (Essex).
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