Zola’s side have now picked up only one point from four games since the Italian’s appointment and this defeat was a huge disappointment as they ultimately allowed Brentford to stage a storming second-half performance after taking a first-half lead through Lukas Jutkiewicz.
Scott Hogan equalised early in the second half and although the free-scoring striker missed a 57th-minute penalty the Bees produced the bitter sting when David Davis deflected a Ryan Woods free-kick past his own goalkeeper, Tomasz Kuszczak.
Brentford completed their outstanding away success in the 87th minute when substitute Nico Yennaris gleefully rammed in a 25-yard drive for the third goal.
With Woods emerging as Brentford’s playmaker, Birmingham found themselves under pressure in the early stages. Leading marksman Hogan was a danger as he demonstrated with a snap-shot which Kuszczak initially fumbled.
The stocky striker buzzed around and looked a potential goalscorer but it was Brentford’s skipper, Harlee Dean, who could count himself lucky not to have given Birmingham the lead on a plate.
Dean made an awful clearance straight to David Cotterill but the Birmingham winger flashed his shot over the crossbar with only Daniel Bentley to beat. In the 19th minute there was an even more clear-cut chance for Birmingham. Che Adams beat Brentford’s offside trap and then conspired to screw his shot wide from about 10 yards.
Four minutes later Birmingham finally took advantage of some dreadful Brentford defending. Robert Tesche pushed forward a through-ball, Dean stumbled badly and Jutkiewicz took full advantage of the defender’s dilemma and stabbed the ball goalwards, and it hit Bentley before going into the net.
Brentford lost all their early shape with Cotterill enjoying almost a free role down Birmingham’s right flank as he set up another goal opportunity for Adams, only for Bentley to make a smart save.
The visitors struggled to regroup, while Birmingham failed to capitalise upon their slender lead. The result was some scrappy play with neither side able to stamp their mark on the proceedings.
Birmingham’s indifferent defending was finally punished in the 53rd minute. Romaine Sawyer glided a low pass from deep on the right, three Brentford players were left unmarked and finally the ball ran into the path of Hogan who blazed his shot into the far corner of the net in the 53rd minute.
The Manchester-born striker, who has attracted a lot of attention this season with his goalscoring exploits, should have given the Bees the lead in the 57th minute when he was brought down by Birmingham’s skipper, Michael Morrison, in the penalty area.
Hogan, however, was a little too nonchalant with his spot-kick and Kuszczak produced a fine blocking save diving to his right.
This was a massive let-off for Birmingham as they had lost most of their first-half sparkle, but further poor defending allowed Brentford to take a 74th-minute lead.
A Woods free-kick out on the left was deflected by Davis, with Andreas Bjelland getting the final touch as the ball slid low into the net.
Salt was rubbed into the Birmingham wound in the 87th minute when Yennaris hammered in a blistering goal from long range, after the Birmingham defence again failed to close down the attacker in possession.