Patchell also weighed in with four conversions and a penalty to finish the day with 16 points. For RGC, there were tries for Alex Schwarz and Lewis Barker while Dion Jones converted one and kicked three penalties to cap an excellent all round display. However, it was not enough for a losing bonus point.
Although victory gave the Blues a two point cushion at the top of the table, victory for the Scarlets in tonight's derby at Parc y Scarlets, will see them leapfrog their closest rivals to once again assume the lead. If the Ospreys win, with a bonus point for scoring four or more tries, they will move into pole position. It promises to be an absorbing night with leading scorer Jordan Williams back in the Scarlets' side having started on the bench in their 23-22 home defeat at the hands of RGC 1404 last month.
Luke Treharne leads the side from full back while the Ospreys will field a full strength side for a game they must win. Sam Davies will be key to their hopes - the outside half and son of Scarlets senior coach Nigel, helped himself to 11 points when the sides met in August, but finished on the losing side as the visitors ran out 36-16 winners at Llandarcy courtesy of 21 points from opposite number Williams.
Blues North moved back to the top of the under 16 ladder on Sunday with a 27-15 victory over RGC 1404 at Rydal School. Jack James, Ieuan Evans, Jon Barnett and Tom Williams made sure of the bonus point while outside half Sam Withers weighed in with two conversions and a penalty. Osian Jones kicked five penalties for the hosts.
The Dragons, who have started the season in decent fashion, can move a step closer to the play-offs should they complete the double over Blues South. The Gwent region were 20-16 winners when the sides met at Cross Keys in August - Hallom Amos, Ashton Hewitt and Mitchell Starr scoring tries and Lloyd Rogers kicking a penalty and conversion to seal the spoils.
Blues South have won only once since then, but will provide the visitors with a stern test on home soil.
Scarlets under 16s: J Evans; J Barnes, J Adams, C Woodall, M Davies; J Maynard, G Rees; C Evans, E Lewis, J Sebastian, J Helps, L Taylor, D Treharne, W Boyde, T Phillips. Replacements: D Thomas, T Myhill, L Watling, C Davies, B Davies, I Bowen, S Evans
Scarlets under 18s: L Treharne (capt); P Rushesha, S Hughes, D Morgan, A Evans; J Williams, R Williams; B Allsop, T Ball, G Thomas, C Morris, C Marks, S Bennett, D Thomas, J Williams. Replacements: J Iles, T Kayjaks, J Meadows, R Jones, C Lloyd,S Maynard, G Owen
Ospreys under 16s: L Popham; A Rowlands, M Burnell, J Thomas, D Howells; J White, D Brooks; L Jonathan, C Forshaw, D Owens, R Morgan, A Williams, J Davies (capt), C Leyshon, C Davies. Replacements: M Davies, S Giovan, G Watkin, T Crowley, M Parmenter, J Preddy, R Bargery
Ospreys under 18s: A Wellington; R Evans, B Roberts, S Lewis, R Williams; S Davies, J Preddy, N Smith, E Yardley, D Suter, J Jones, R Hughes, E Williams, L Wilson, M Jenkins. Replacements: A Evans, R Thomas, G Reeds, T owen, M Davies, R Dudley Jones, D Palmer