Aston Villa loanee Jaden Philogene scored the only goal of the game to condemn Birmingham to a 1-0 defeat in the Sky Bet Championship at Cardiff.
Steve Morison’s men defied the sweltering conditions to produce a superb display of high-energy passing football in the first 45 minutes, playing out from the back and attacking Birmingham with pace and precision.
Key to that approach were skipper Ryan Wintle, who pulled the strings in midfield, and Callum O’Dowda, who threatened every time he got the ball on the right wing.
And the pair combined to create the winner for 20-year-old winger Philogene after 17 minutes.
Wintle had dragged a shot a yard wide from the edge of the area after only three minutes as the Bluebirds started as they meant to go on.
And John Ruddy made a double save to deny Romaine Sawyers and Max Watters from close range after good work from Mahlon Romeo and O’Dowda on the right flank.
Before a defence-splitting ball from Wintle inside Birmingham left wing-back Przemyslaw Placheta released O’Dowda again and he had the simple task of picking out Philogene in the middle for a tap-in.
The hosts lost some momentum due to a drinks break midway through the first half and they were indebted to Jamilu Collins for preserving their lead after half an hour.
The left-back made a perfectly-timed tackle to deny Scott Hogan a shot on goal when the striker was set to pull the trigger with only goalkeeper Ryan Allsop to beat.
Cardiff soon recovered their composure, however, and they should have extended their lead before the break.
Philogene cut inside and shot straight at Ruddy from 20 yards before O’Dowda played in Watters through the middle but the goalkeeper closed him down and saved with his leg.
The Bluebirds then twice missed the opportunity to play in Andy Rinomhota before the hapless Watters mis-controlled O’Dowda’s cutback into the box and the chance was gone.
Watters was replaced by Mark Harris for the second half and Cardiff continued to create chances with O’Dowda seeing one shot blocked by Marc Roberts and another saved by the boot of Ruddy.
But Birmingham were improved and they thought they should have had a penalty when Hogan went down in the box after a tangle with Cedric Kipre but referee Darren Bond was unmoved and booked the striker for his protests.
Substitutes Harris and Kion Etete combined for what should have been the second goal for Cardiff 11 minutes from time, but the latter headed wide at the far post.
O’Dowda was then denied a penalty when he appeared to be shoved over in the box as Cardiff held on for a deserved win.
