The home side’s victory at Llantwit Fardre leaves them with 26 points whilst a losing bonus point for the Scarlets means they are a single point ahead of the Ospreys, who travel to Sardis Road next week to face the Blues North.
A victory for the Ospreys will see them into the March 5th final, at Pontypridd, whilst a losing bonus point means try count would determine whether the Ospreys or Scarlets would go through to meet the North.
The U16 encounter, that was rearranged from December 12th, saw tries from flanker David Barry, centre Sam Campbell and fullback Josh Wills, plus two conversions and a penalty from outside half Joseph Griffin that put the hosts into a commanding 22-6 half-time lead.
However, tries from centres Dale Ford and Luke Williams put the Scarlets within six points as the game moved into its final quarter.
Griffin kicked a penalty to make it 25-16 and that, in the end was enough, despite two further penalties from the Scarlets in the closing stages.
