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.
The WRU's Women and Girls legacy events - #TRY OUR GAME have proved popular this week with current players and newcomers to the game learning new skills and picking up tips from national squad players.
We caught up with Shona and Ellie from the Wales women team ahead of the start of the Women's Rugby World Cup in Paris next month at a recent women's training session to encourage and promote more women and girls to try their hand at rugby. #tryourgame
The Women's Rugby World Cup warm-up clash between Wales and USA proved bittersweet for centre Elen Evans. Despite being one of the star performers on the day on her 50th Test appearance, USA edged home 10-7 at Cross Keys.
Wales completed their Junior World Championship campaign with a victory over Samoa. Team manager Mark Taylor and No 8 James Benjamin reflect on a tournament which saw Wales win three games and lose two.
Wales U20 players Angus O'Brien, Nicky Thomas and coach Richard Hodges are determined to finish their Junior World Championship with a flourish when they tackle the big hitting Samoans tomorrow in Auckland.