Cardiff City extended their unbeaten run over Birmingham to eight matches as they deservedly took three points in a one-sided 1-0 win in the Welsh capital.
Cardiff led after a fast start when Jaden Philogene tapped home from close range on 16 minutes, finishing a sweeping Bluebirds attack.
The hosts should have added to their lead but missed a host of chances.
Birmingham saw a second-half penalty appeal waved away as their miserable recent run in Cardiff continued.
Cardiff fans will be happy with what they saw from their side, who look a more progressive and cohesive team than the one that spent much of last term battling relegation.
Bluebirds manager Steve Morison - who has made 15 summer signings - made two changes from the side beaten at Reading last time out in the Championship, with only Philogene retained from the Cardiff team thrashed in midweek by Portsmouth in the EFL Cup.
Cardiff impressed in their opening day home win over Norwich City and threatened to take a quick lead when the ball fell kindly to Ryan Wintle after only three minutes, but he dragged his shot wide.
That move came after good play by Mahlon Romeo and Callum O'Dowda, and the two combined again on seven minutes as Cardiff were left wondering how they did not score as John Ruddy made a fine double save to deny Romaine Sawyers' initial effort and Max Watters' close-range follow-up.
Cardiff continued to cause huge problems for Birmingham down the right flank and, from another smart move, O'Dowda went clear of the Blues' defence and squared for on-loan Aston Villa player Philogene, who was left with a tap-in as Cardiff turned defence into attack in an instant.
It took the visitors 30 minutes to even threaten Cardiff's goal, and when they did they should have drawn level as Scott Hogan raced clear, but defender Jamilu Collins produced a superb tackle to deny him.
The hosts also missed a brilliant chance before half-time with Watters sent clear by the lively O'Dowda, but Ruddy spread himself and was able to divert the ball around the post, with Birmingham lucky to only trail 1-0 at the break.
There was no obvious change to the pattern of play with Cardiff seeing two O'Dowda efforts on goal blocked within five minutes of the restart.
The visitors thought they had found a route back into the game when Hogan tumbled in the penalty area and screamed for a penalty on 51 minutes, but referee Darren Bond instead pointed for a goal-kick and booked Hogan for simulation.
The visitors improved after their penalty appeal and were encouraged by Cardiff's failure to score a second goal while they were dominating the contest.
Cardiff might have gone clear with a counter-attack that saw substitutes Rubin Colwill and Mark Harris combine, but Etete headed wide with the goal gaping, before O'Dowda saw a credible penalty appeal waved away.
However, the hosts deservedly held on with substitute Sheyi Ojo curling just wide as Cardiff finished the contest in control.
Cardiff City: Allsop; Romeo, Kipre, Ng, Collins; Wintle (C), Rinomhota, Sawyers (Colwill 63’); O’Dowda (Ojo 82’), Philogene (Etete 63’), Watters (Harris 45’). Subs not used: Alnwick, Simpson, Ralls.
Birmingham City: Ruddy, Sanderson, Roberts (Williams 54’), Trusty, Colin, James, Chang (Hall 75’), Bacuna (Leko 75’), Placheta, Hogan, Deeney (C) (Jutkiewicz 72’). Subs not used: Etheridge, Friend, Bellingham.