An away win will seal the Blues' passage into the final, whilst a home win will help the Ospreys in their bid to buck the recent trend. It was 41-7 to the Blues when the sides met at Cardiff Arms Park back in September.
The Dragons, who are fourth, with only 10 points from their six games, must win their final two pool games and hope that either the Ospreys or Scarlets lose both of their remaining matches. Tonight, they make the long trip west to face the Scarlets at Parc y Scarlets.
The play-off places at Under 16 level have already been decided with Blues North, Ospreys, Dragons and Scarlets all safely through to the semi-finals. Tonight sees the North take on the Ospreys at Abercwmboi and the Dragons entertain the Scarlets at Cross Keys.
For the Ospreys, victory this evening will all but assure them of top spot in the pool - they are currently four points clear of a North side desperate for revenge after losing 10-8 at Llandarcy back in early September. A Jarrod Evans penalty and an unconverted try from Shaun Clarke looked to be enough for the North as they led 8-3 late in the game.
However, a last gasp converted try from Liam Popham sealed the visitors' fate and left them nursing a first defeat of the season. Since then, they have lost only once - seven days ago at Parc y Scarlets.
Blues North team manager Nigel Way has been delighted with his side's progress this season and admits that a seventh win in nine games would further confirm the emergence of his Class of 2010.
"It has been an excellent season all round and we are delighted to find ourselves in such a promising position," said Way. "Victory tonight, is not as crucial, but it would certainly give us greater momentum as we move towards the play-offs."