Llantrisant remain top of Division Two East after beatings Fleur de Lys by a 21 point margin.
Gavin Groves, Jonathan Williams and Ian Worgan ran in three tries for the league leaders in a 28-7 victory.
Tredegar jumped to second in the table after routing Mountain Ash 28-0 away from home.
All the scoring came in the second half with the visitors notching a bonus point through their four tries, two of which came from Jamie Henthorne.
The other two teams making up the top four, Gilfach Goch and Brynmawr, drew 10-10 in their clash at Welfare Park.
Bedlinog were another side who picked up a bonus point win, crossing five times in a 36-12 win at Treherbert.
Elsewhere Ynysybwl beat Abergavenny 17-12 and Abercynon won 23-8 at Rhydyfelin.
New Tredegar picked up their first win of the season in Division Three East, beating local rivals Rhymney 18-6.
Two second half tries from Dewi Winstone and Steve Osbourn were enough to lift the home side off the bottom of the table.
They rise above Abertillery Blaenau Gwent, who were defeated 22-11 by leaders Nelson, and Cwmbran, who lost 32-25 at Gwernyfed.
In a battle of the bottom two in Division Four East Risca thrashed Pontllanfraith 35-0, picking up their first league win of the season and with it their fifth bonus point.
The local derby between Rhiwbina and St Joseph's was won 10-3 by the hosts, with Danny Hobbs scoring the winning try for the Squirrels.
Centre Andy Farrell lived up to his famous name as he scored two of Usk's four tries in their 28-21 win over RTB Ebbw Vale in Division Five East.
Trinant clinched a losing bonus point as they came back from a 17-0 half-time deficit against Talywain, narrowing the scoreline to 17-13 by the end.
Callum Jones and Leon Probert crossed for Talywain in the first period.
Hartirdge made it two wins in two games in Division Six East, beating the morning leaders Crickhowell 26-6.
Blackwood Stars capitalised on Crickhowell's defeat by beating Markham, who started the day second in the table, 22-10 to take top spot on try difference.
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