Cwmllynfell closed the gap at the top of the table to 16 points after securing a 27-20 win at home to Kidwelly. There was no bonus point for the hosts despite captain Gareth Jewson scoring two of his side's three tries.
Also in Division One, there were home wins for Carmarthen Atletic, Loughor and Skewen against Kenfig Hill, Ammanford and Aberavon Quins respectively.
Elsewhere, in Division Two there was a major shock after second-placed Seven Sisters were demolished by an inspired Penclawdd side who claimed an astonishing 43-8 win.
Builth Wells capitalised on their nearest rival's slip-up after brushing aside Aberystwyth 35-6 - extending the gap between first and second to six points.
In Division Three, leaders Amman United thrashed visiting Pontyberem 64-12 to maintain their strong grip on the title.
While in Division Four, Llanybydder leapfrogged Tycroes to first place on points difference after they beat Laugharne 34-5, and Tycroes lost 21-12 away to third-placed Trimsaran.