In SWALEC Division Two East, Mountain Ash closed the gap on league leaders, Gilfach Goch, thanks to a 33-21 win over fourth-placed Brynmawr.
The vital win on the road keeps them in the hunt for promotion. Brynmawr stuck with three tries but it was not enough to overcome the visitors, who scored tries through Merion Thomas, Craig Evans, Dale Keeping and Dean Philips to secure maximum points.
Treorchy also kept their chances alive with a bonus-point home victory over Penallta, Shaun Green, Damon Filmer, Andrew Mallin and Peter Hutchings the men who crossed for the hosts.
However Gilfach Goch, who were not in action this weekend, can win the title and promotion to Division One East with a bonus-point win in a crunch match against Treorchy on Friday.
Elsewhere in the division, Llanharan secured their place in the league for another year with a hard-fought victory over Llantwit Fardre.
Fleur De Lys will join Llanharan in the division next year after they were crowed Division Three East champions, recording a 29-17 win over Gwernyfed on the road. Back-row duo Leigh Taylor and Lee Jones were joined by Jamie Heythorn to touch-down and Paul Emanuelli slotted a further 14 points.
Meanwhile Pill Harriers ran in nine tries on their way to a 61-7 triumph over Croesyceillog. Ross Palmer was in magnificent form and the fly-half inspired the Harriers to victory with a five-try brace.
In a titanic battle in Division Four East that saw league leaders Abertillery BG travel to second-placed Risca. The visitors came out on top and took a giant leap towards securing the Championship thanks to a closely fought 18-13 win. Wing Aled Penn proved the difference and raced away to score two vital tries.
League strugglers, St Josephs, scrapped to a crucial win in their battle to avoid the drop, securing 15-13 win at Abercarn, Nigel Morgan and Ryan Moore the try scorers for St Jo's.
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