QPR succumbed to a 2-1 defeat at St. Andrews, with the awarding of a hotly-disputed penalty in the 63rd minute costing the R’s dear.
Rangers felt aggrieved when Nedum Onuoha was punished for an alleged push inside the box – and Paul Caddis stepped up to slam home the resultant penalty.
Earlier, Matty Phillips’ third goal of the season on 17 minutes put Chris Ramsey’s side in the ascendancy, only for Paul Robinson to equalise soon after with a free header.
Chances were at a premium after the Blues took a 2-1 lead, as the R’s left the Midlands pointless, to the disappointment of the travelling 1,676 Hoops fans in the away end.
Head Coach Ramsey made two changes from the R’s last outing against Bolton Wanderers prior to the international break, with James Perch and Sandro both starting.
Rob Green was named in goal, with Perch and Paul Konchesky filling the full-back berths either side of centre-half duo Grant Hall and skipper Onuoha.
In midfield, Sandro made his first start of the season alongside Karl Henry, with a three-pronged attack of Phillips, Leroy Fer and Tjaronn Chery supporting Jay Emmanuel-Thomas, who led the line once again in the absence of Charlie Austin.
On a chilly October afternoon in the Midlands, Rangers settled well, with Fer and Sandro seeing plenty of the ball in the opening exchanges.
However, it was Birmingham who mustered the first opportunity of note in the 11th minute, courtesy of Demarai Gray.
The highly-rated Blues wide-man took one touch to set before drilling a fearsome 15-yard drive, which Green did well to save down low to his left.
But it was Rangers who opened the scoring on 17 minutes – thanks to Phillips’ third goal of the season.
Onuoha’s cultured ball back into the Blues box was seized upon on by the R’s winger, who turned and fired a left footed shot on goal, which ricocheted into the back of the net via Jonathan Grounds, completely wrong-footing Tomasz Kuszczak.
Eight minutes later, Perch picked up his fifth booking of the season for a poorly-timed challenge on Jacques Maghoma – and from the resultant free-kick, the R’s paid the ultimate price.
Gray’s in-swinging free-kick found its way to the back post, where Robinson was left unmarked to head the hosts on terms.
The game continued to ebb and flow from end-to-end and on 33 minutes, Chery forced Kuszczak to parry his 30-yard free-kick, before the Dutchman crafted another opportunity a minute later, this time seeing his shot blocked.
Neither side were able to muster any other chances of note in the remainder of the half, as the teams headed into the break on level terms.
Birmingham came out the blocks quickest after half-time, with Maghoma’s low cross on 51 minutes diverted away by Onuoha for a corner.
At the other end, Chery’s curling effort brought the best out of Kuszczak, as both sides went in search of the all-important third goal of the game.
The R’s looked a threat on the counter as the game went on, with Phillips cutting in from the left flank, only to see his low shot well saved by Kuszczak.
That saved proved to be crucial, because just moments later, Onuoha was penalised for a foul in the box and Birmingham took the lead.
Caddis fired his spot-kick straight down the middle, to the delight of the home faithful.
Onuoha, clearly aggrieved at the decision to award the penalty, was booked for his protestations after the goal.
To their credit, Rangers responded well to going a goal down, with Fer firing a yard wide of the target, with Kuszczak scrambling across his line.
Ramsey made a double change on 71 minutes, introducing Massimo Luongo and Daniel Tozser at the expense of Sandro and Leroy Fer.
Those changes – and the late introduction of Seb Polter – failed to have the desired effect though, as the Blues held on for a narrow victory.