Neil Warnock left Swansea a beaten man. It was the first time in seven visits he has had that experience.
The Bluebirds manager had a good record in West Wales, with one win and five draws in six visits, but he was left down and out by this defeat.
Cardiff never really got going. They were desperately off-key defending set-pieces. Ben Willmott was left unmarked when he scored the winner after 24 minutes. That happened far too often.
Warnock’s men are big and strong. They are not the pure footballing team that Swansea can be, but Cardiff should be strong and dominant from set-pieces at both ends of the pitch.
They were, though, sloppy at the back and probably even worse in attacking terms.
Gavin Whyte continued his progress at Championship level and Nathaniel Mendez-Laing gave Kyle Naughton a game, but too many Bluebirds were below par.
Swansea went in to the clash with Cardiff having failed to win in in their last three Sky Bet Championship matches, while the visitors are still waiting for a first away win.
Cardiff captain Sean Morrison and Aden Flint struggled to keep things tight at the back, while goalkeeper Neil Etheridge looked nervy and anxious at times.
Equally, the Bluebirds failed to create enough going forward, despite starting with Robert Glatzel and Danny Ward in attack.
The partnership between the two strikers failed to find a spark and Omar Bogle took over from the injured German forward Glatzel just after the hour.
Playmaker Lee Tomlin failed to even make the subs bench, who, like Junior Hoilett, pulled up in training yesterday. How the Bluebirds needed Tomlin’s vision and awareness at times.
There is no doubt Cardiff players gave everything in the battle, throwing their bodies in front of shots and working 100 per cent for 90 minutes.
Personally, though, I can’t see enough quality in this team to suggest they will compete for automatic promotion or a play-off slot.
They have power, strength ands physical presence, but they need that extra touch of class. Perhaps Warnock can find that added ingredient in January when the transfer window opens.
Swansea are far from a top Championship team, but they will take immense pride and satisfaction from this South Wales derby win.
The Bluebirds have to improve. They must get better if they are to launch any kind of challenge for a top six challenge.
On the evidence of this match, they are some way off right now.