Cardiff made it a quickfire double over their near neighbours as they rattled up five tries without reply in the first-half to continue their good end to the season.
Having beaten Caerphilly 38-8 at the Arms Park eight days earlier, they matched that tally in the opening 40 minutes to pile on the points and consolidate their fourth place in the Welsh Premiership.
It was Wales full back Rhys Williams who started the early flourish as he ran in a solo try after 18 minutes. By the interval Dean Dewdney, Adam Jones, Don van Vuuren and Ryan Powell had followed suit.
It was not the kind of start that former Cardiff and Wales great Mark
Ring had been hoping for from his home side, especially as they have a major European final to come in two weeks time when they face Castres in the Parker Pen Shield final in Reading.
Things went from bad to worse shortly after the break when Wales utility back Iestyn Harris hoisted his match tally to 20 points with a try and a sixth conversion to further stretch the lead.
But far from throw in the towel, Caerphilly rallied and two more penalties from outside half Luke Richards gave them new hope. Then two tries in the space of four minutes, both converted by Richards, breathed new life into the final quarter.
Wing Ryan Howells crossed for the first of the home tries and then lock Darren Davies romped over moments after his opposite number Heino Senekal was sent to the sin-bin. But all that was left in the game were two more penalties from the two outside halves and Cardiff hung on for victory.
Caerphilly: Tries: R Howells, D Davies; Cons: L Richards 2; Pens: L Richards 6.
Cardiff: Tries: R Williams, D Dewdney, A Jones, D
van Vuuren, R Powell, I Harris; Cons: I Harris 6; Pens: I Harris 2.
Wales Head Coach Rob Howley talks to WRU TV's Sebastian Barrett about the 36-man squad he has just named for the forthcoming Under Armour series, which includes two uncapped players, Ospreys duo Sam Davies and Rory Thornton.
Head coach Rowland Phillips is deligthed he can now call BT Sport Cardiff Arms Park home for his Wales Women's side, who launch their international season next month with games against Scotland and UK Armed Forces in the heart of the capital city.
Wales Sevens star Sam Cross has put his home town club of Brynmawr on the map after winning a silver medal at the Rio Olympics with Team GB. His club have now honoured him by naming their players bar after him, as WRU TV discovered at the official launch, recently.
One of the newest members of the Principality Premiership, Bargoed admit it's proving to be a steep learning curve at the highest level, but are determined to become a force to be reckoned with. WRU TV visited the club last weekend when they took on Llanelli.
Table-topping Aberavon travel to north Wales to tackle RGC 1404 as both teams defend unbeaten starts to the season in the Principality Premiership. WRU TV's Graeme Gillespie visited the Wizards to see how their preparations were going for the game of the weekend.
The Half a Game initiative is currently sweeping across Wales and proving a major success. The scheme aims to give every young player at least half a game every weekend. WRU TV recently visited a festival in Narberth where clubs have fully embraced the initiative.
Both Bargoed and Swansea were seeking their first win of the Principality Premiership season this afternoon. It proved a fruitful day for the hosts - not only did they win, but Bargoed claimed a try bonus point.
Cardiff managed to keep their unbeaten record at home intact, but only just as Bridgend made them work extremely hard before the Blue and Blacks secured a hard fought Principality Premiership win at the BT Sport Arms Park last night.
Former Wales back row Andy Powell gives a guided tour of The Wern, home of Merthyr RFC, who are determined to prove a lot of people wrong and make their mark in their first season in the Principality Premiership.