Outside-half James Hook scored a splendid solo try and converted as well as converting tries by wings Richard Johnston and Aled Brew and slotting four penalties in a 23-point haul.
Newport kept in touch with a convincing 43-13 win over Carmarthen Quins. A brace of tries from centre Richard Payne sent the Black and Ambers on their way while Quins' centre Emyr Jones grabbed his 100th league try as a late consolation.
Caerphilly finally lost their fight to avoid relegation as they went down to 14-man Llandovery at Virginia Park despite visiting prop Andrew Jones getting his marching orders midway through the second half.
Gareth Thomas and Tom Hearne scored late on but it was not enough to save Caerphilly from the drop and a 41-24 loss with Gareth Morgan kicking seven goals for the Drovers.
Bridgend came from behind to beat Swansea 21-14 at St Helen's thanks to second-half tries by Brendan Roach and Ryan Howells after Rhodri Wells had put the All Whites ahead.
Wing Darren Berry helped himself to a hat-trick as Pontypridd staged a stunning turn around to smash Bedwas 71-5 just three days after losing to the same opposition.
Pontypridd's cup semi-final opponents Aberavon warmed up for next Saturday's clash with a surprisingly convincing 43-15 win over Cross Keys with influential No 8 Richard Morris going over for two of the six tries by the Wizards.
Ebbw Vale crossed Llanharan's line four times in their 31-12 success at Eugene Cross Park after the visitors had led at the interval.
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