Cardiff Men Under-18s routed their Dragons counterparts 19-48 in the WRU Regional Age-Grade Championship at Ystrad Mynach on Sunday.
The Blue and Blacks were in devastating form and put in a dominant all-round display as they ran in seven tries.
Winger Ollie Das opened the scoring with a try in the 12th minute, and number eight Evan Rees crossed over again shortly after.
Dragons struck back with a try of their own but it was cancelled out by Osian Darwin-Lewis with Lloyd Lucas adding the conversion.
The home side then scored their second try of the game to move within three points of Cardiff but Lucas slotted a penalty just before half-time to make the score 14-20 heading into the break.
The Blue and Blacks came out firing in the second-half as substitute Sion Davies scored two tries withing the space of minutes and full-back Finley Hart touched down in the 60th minute as Cardiff opened up a 14-41 lead.
Dragons scored a consolation try but the visitors capped off the performance with a second try of the game from Das. Fly-half Lucas added the conversion to finish with six successful attempts on goal from eight.