Brentford suffered their second home defeat in a week, going down 2-0 to mid-table Birmingham.
Former Bees striker Clayton Donaldson rubbed salt in the wounds of his old teammates, racing clear to give the scoreline a flattering look deep into injury time.
Michael Morrison had given Blues the lead after 71 minutes, rising unmarked in the box to power home a header from a pinpoint David Cotterill corner.
The setback capped a miserable week for Brentford, who sacked head coach Marinus Dijkhuizen just nine games into his Griffin Park reign.
It was a miserable baptism for former Blues man Lee Carsley, whose new charges looked devoid of any creativity in the final third.
Brentford rarely threatened Birmingham keeper Tomasz Kuszczak's goal, the only real efforts of note a first-half Marco Djuricin snapshot and a late Alan Judge effort.
The forward cut in from the right past four Birmingham defenders only to see his rising drive flash to safety off the top of the bar.
Early on there was only one side in it, Gary Rowett's men looking bright and incisive with Demarai Gray twice testing Bees keeper David Button.
Brentford's sole striker Djuricin, who grew more removed from the action as the game wore on, flashed two efforts wide in the early stages when he should have tested the keeper.
His best effort came on 25 minutes when he fired in an instinctive low drive from Jake Bidwell's driven low cross, but Kuszczak was equal to it.
At the other end Button had to be at his best on the half-hour, going full length to tip Cotterill's placed header past the upright.
After the break Lasse Vibe, another of the Bees' statistics-led signings, flashed a low drive past the far post when he should have done better.
Minutes later he raced onto a Toumani Diagouraga through-ball only to fire straight at the relieved Blues stopper.
Brentford had all the possession, working the ball around the midfield, but when it came to a final ball they were badly lacking.
And as Birmingham grew more into the game, a breakaway goal always looked on the cards.
The breakthrough came when Jonathan Grounds' shot was deflected behind and, from the corner, Morrison rose unchallenged to head powerfully home.
Brentford grew increasingly desperate in the dying stages and Judge threatened before Harlee Dean forced a goal-line clearance in a melee.
But luck was not on the Bees' side and when Donaldson sped free to draw Button and dink the ball over the prostrate keeper, Griffin Park emptied.