Leaders Ebbw Vale came back to earth with a thump at mid-table Aberavon, losing 39-19 as Wizards fly-half Jamie Davies scored a try and kicked fourteen points.
Second-placed Pontypridd took immediate advantage of Vale's slip up with a 22-12 win over Cross Keys.
Cardiff ran in six tries, including a brace to No.8 Chris Jones, which all converted by Craig Evans in their crushing 42-21 win over bottom club Llandovery. All of the Drovers' points came from the boot of John Elrick.
Winger Steve Cullen scored the vital try in Glamorgan Wanderers' 11-10 victory at Bedwas, while Gareth David's two penalty goals proved the difference in Bridgend's 14-8 home win over Llanelli.
Dan Griffiths supplied seventeen points in Newport's 22-10 win over Swansea at Rodney Parade.