Glynneath shocked visitors Ammanford with a 39-7 home win. Craig Moses and Rhodri Cole were among the try-scorers for the hosts who remain two places behind Ammanford in eighth position.
Fifth-placed Llangennech demolished strugglers Aberavon Quins in a 64-7 victory. Ellis Phillips scored a hat-trick of tries for the home side who won their fifth game of the season.
Kenfig Hill brushed aside Kidwelly in a 40-25 win at home, while Carmarthen Athletic enjoyed a precious 19-11 win against Skewen. The result leaves Skewen languishing in 11th place - five points clear of bottom-side Aberavon Quins.
Builth Wells continued their dominance of Division 2 West after securing a hard-fought 20-15 away win at Maesteg Harlequins.
In Division 3 West, Amman United strengthened their grip at the top after a bonus-point victory at home to Llanelli Wanderers. The hosts won 34-10, and the result leaves the Wanderers in fifth place - 12 points off the pace.