Saracens completed a clinical 29-0 win over Pill Harriers, and have the added bonus of two games in hand. Harriers restricted the home side to 8-0 at the break, but had few answers in the second spell.
At the other end of the table, Brynmawr went desperately close to their first points of the season before losing 22-17 at home to Llantrisant, and they have now gone 19 matches without so much as a draw.
Abergavenny have a nine-point lead in Division 3 East after their 19-7 victory at Pontllanfraith, while bottom-placed Risca - who lost their first 15 matches - have now won three out of five after a 14-0 win over Abercarn. Prop Nicky Davies and outside-half Matthew Johnson scored tries for Risca.
Division 3 South-East was wrecked by the weather, with only three of the seven scheduled games going ahead. Ruthin cemented their mid-table position with a 31-0 win over nearest rivals Aberdare, helped by try doubles to centres Gethin Hughes and Tom Pettit. Treherbert join Ynysybwl at the top of the table with a hard-fought 8-3 victory at Pentyrch.
Garndiffaith smashed Oakdale 71-5 to confirm their top spot in Division 4 East, with second-placed St Peters staying in touch thanks to an impressive 22-3 win over
Tredegar Ironsides. Fullback Steve Mayley scored four tries for Garndiffaith, with outside-half Craig Selway scoring one and slotting eight conversions.
In Division 4 South-East, Penallta have moved to within two victories of the title after a 39-0 mauling of Penygraig. Penarth, the only other club in with a shout of topping the table, beat Llantwit Major 17-0, but have played four more games than Penallta.
Machen retained their perfect Division 5 East record with a 13-10 victory at Bettws, but the biggest cheers of the day were at RTB Ebbw Vale, who recorded their first win of the season - a 25-7 result over St Josephs. Stuart Dicks and Steve Boland scored tries for the winners.
Porth are this season's Division 5 South-East champions after a 6-3 victory at Rhiwbina on Saturday. Nearest challengers Bridgend Sports lost 12-0 at Cefn Coed, giving Porth a 12-point lead with only two games remaining.
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