Builth Wells remain top in Division Two West but they will do well to keep looking over their shoulder at ever-improving Bridgend Athletic.
Flanker Andrew Duggan scored the game's only try as Builth made hard work of seeing off struggling Penclawdd, 13-6 at the Groe. And it is just that lack of tries that could undermine their title credentials.
The Bulls have won five from five but only once have secured a bonus point and that means Loughor, 28-23 winners over Ammanford, are just one point behind with a game in hand.
But sat on both their shoulders are Bridgend Athletic who are also unbeaten after easing past Kidwelly 36-13. Athletic are still eight points behind the leaders but with two games in hand and a red hot finisher in their ranks such as Rob Coles, who took his scoring streak to seven tries in three games with another double, they must be taken seriously.
Pencoed broke their duck thanks to a hat-trick from skipper Gareth Jenkins in their 43-21 win over Gorseinon who are now four points adrift at the foot of the table after Mumbles, Penclawdd and Cwmavon all picked up points.
Aberystwyth ran in 13 tries in their 75-0 rout of Tumble in Division Four West but are still six points behind leaders
Pontyberem who found the going much harder at Lampeter Town before winning 13-9.
Tondu top Division Three south-west after a 9-0 win at Seven Sisters while Brynamman continue to control Division Four, following their 36-0 victory over Cwmgors.
Vardre lead the way in Division Four south-west after beating Neath Athletic 17-12 while Milford Haven crossed eight times against Swansea Uplands in Division Five.
Wales reached their first semi-final since 2013 in the opening round of this season's HSBC World Rugby Sevens Series in Dubai. WRU TV's Graeme Gillespie recaps on what proved to be an eventful tournament
Wales and Ospreys back row James King, who came through the North Wales age grade system, nominated North Wales Regional Community Rugby Manager Marc Roberts, in the WRU's 'Diolch' initiative where squad players thanked those who played a part in their rise to the top.
Beating Merthyr has boosted Carmarthen Quins hopes of reaching a top eight spot in the Principality Premiership. Quins captain Haydn Pugh is delighted with his team's progress and is determined that everyone from the Under 6s through to the senior team, enjoys the ride.
When the Wales squad were asked to nominate individuals who played a big part in their early playing days, Wales and Dragons full back and wing Hallam Amos thought of his former Monmouth School rugby coach John Bevan.
Sam Cross and Luke Treharne have been named as co-captains of the Wales Sevens side as head coach Gareth Williams names his 12-man squad to play in the first leg of the HSBC World Series in Dubai next weekend.
Bedwas head coach Steve Law and players Nicky Griffiths and Alun Rees extol the virtues of the close knit club as they prepare to host third place RGC 1404 - who are one place head of them on the Principality Premiership points table - on Saturday.
Many of the Wales squad have said Diolch (thank you) to someone who played an important part in their early playing days by nominating them to be invited to the Wales v South Africa match. One person, Gowerton Comprehensive geography teacher Mr Dean Mason was nominated by two of his former pupils, Dan Biggar and Sam Davies.
The second WRU disability rugby pilot has been delivered, this time in Caerphilly schools, culminating in a festival at the Caerphilly Centre of Sporting Excellence, Ystrad Mynach tomorrow. Plans are in place to set up a Disability Rugby Club in Newbridge to provide long-term playing opportunities.
WRU TV: Hear from inside the Wales camp as Neil Jenkins discusses this weekend's clash with South Africa and how the squad are looking to put in a strong performance to round of the 2016 Under Armour Series