The kicking prowess of Scott Maynard was not enough to defeat the Athletic who went over twice courtesy of Viv Jenkins and Rhys Jones.
In the other two games that went ahead in the top tier, Kidwelly eased past Ammanford and secured a bonus point in a 41-23 victory.
There was a close encounter between Loughor and Llangennech as the match finished 16-15 to the home side. The hosts remain in tenth position, while Llangennech move to fifth.
In Division 2, travelling Builth Wells scraped past Penclawdd in a 20-19 win. The result keeps them at the top of the table while Penclawdd stay in ninth.
Second-placed Seven Sisters had to settle for a 12-12 draw against Taibach, who are in danger of replacing Haverfordwest at the foot of the table after they claimed their first win of the season against Maesteg Quins in a 13-8 away win.
Elsewhere, Amman United secured another bonus point to hold on to the Division 3 top spot with a 40-19 win over Cardigan. Newcastle Emlyn remain hot on their heels however, after they comprehensively disposed of Milford Haven in a 50-10 victory.
