Cardiff Blues North Under-16 and Cardiff Blues South Under-16 extended their 100 per cent records in the WRU Age Grade Championship on Wednesday.
The sides are going head-to-head for this season's title, and it could come down to the final match of the season, with the inter-regional derby being held at Cardiff Arms Park on Wednesday, February 28.
Cardiff Blues South currently sit on top, six points ahead of Cardiff Blues North, who have a game in-hand.
Cardiff Blues South 31 Scarlets East 12
The visitors took an early lead at the Cardiff Arms Park, through captain Nick Frampton.
Osian Thomas' conversion was off-target, but Scott Andrews' side would soon bounce back.
Benji Williams secured a quickfire brace, twice converted by Gethin Rosser, which saw Cardiff Blues South head into the interval with a 14-5 advantage.
Scarlets East seemed to have fought their way back into the game following a second half try from Caine Rees-Jones, but were immediately dealt a major blow, as Zach Lloyd crossed twice to seal a bonus point for the home side and put some breathing space on the scoreboard.
Jamie Howells put the cherry on the icing with a try in the final moments.
Dragons South 5 Cardiff Blues North 57
Hooker Corben Evans scored a hat-trick, as Cardiff Blues North comprehensively defeated Dragons South at Ystrad Mynach.
The visitors scored 50 unanswered points, as Kian Beach, Shaun Webber, Harrison Chapman, Ethan Fackrell and Rhys Thomas also got in on the scoring.
The hosts did cross the whitewash for a consolation score, but Cardiff Blues North had the last word as Tyler Morris touched down in the final play.