At the other end of the table, Tonna clinched a potentially crucial win at Pontyberem, 31-20, in their fight to stay up to open a three-point gap over bottom side Seven Sisters.
Tumble were crowned Division Three champions in emphatic style with a 52-0 hammering of third-place Llangefni, despite Aberystwyth's win at Pontarddulais.
Division Three South West winners Mumbles put the icing on their title celebrations with a 73-22 humiliation of struggling Bryncoch who are now hovering precariously above bottom sides Banwen and Brynamman who both registered important wins.
Division Four South West leaders Briton Ferry won their last fixture of the season but face an agonising wait as BP Llandarcy have two games to overturn their three-point lead for the title.
Ystradgynlais will take the Division Five South West title to the final week with their 54-29 win at Cwmgwrach.