Principality Premiership newboys Pontypool were denied a dream start to the season after they were squeezed out by reigning champions Neath 36-31 at The Gnoll.
Pontypool returned to the Premiership as Division One East winners and rocked the four times champions with three tries, including a brace from centre Phil Price.
Geraint O'Driscoll also booted 16 points as 'Pooler' recovered from the loss of prop Nicky Blake, who broke his leg in the second half.
But Ospreys youngster Kristian Phillips and Gareth King both scored twice to save the blushes of last season's double-winners in front of their home crowd.
"We expected it to be difficult and Pontypool didn't disappoint us," said Neath coach Rowland Phillips.
"We were playing against a team we didn't really know much about and we didn't play well enough. It simpy wasn't good enough as far as our standards are concerned.
"We have been successful int he past, but as far as I'm concerend all of that is in the past. We have to build moving forward."
Despite the loss of British Police prop Blake, who is likely to miss much of the rest of the season, Pontypool coach Gareth Lintern was bullish about the start his side made back in the big time.
"We had been looking forward to this game ever since last season. It was a superb performance and we are bitterly disappointed we didn't win it," said Lintern.
Aberavon made the perfect start to the new campaign with a 29-27 victory over local rivals Swansea at St Helen's.
Ian Moore, Dai Pritchard, Richard Morris and Luke Hatherway all went over to clinch a bonus-point victory for the Wizards despite a late recovery by the All Whites.
Richard Kelly crossed twice to clinch two consolation points for Swansea's losing margin and scoring four tries.
Scarlets outside-half Rhys Priestland was on target as Llanelli beat Glamorgan Wanderers 24-13 at Stradey Park. Adam Powell, Daniel Evans and Ian Jones all scored while Priestland kicked seven points.
Ebbw Vale have finished in the Premiership's top four for the past two seasons but were held to a surprise 6-6 by Bedwas.
Dai Langdon and Andrew Williams both converted penalties for the Steelmen but Phil Dollman struck twice to share the points at Eugene Cross Park.
Rory Pritchard and Carl Hocking grabbed tries as Bridgend won 20-8 at Llandovery who saw prop Craig Cross sent off a minute after coming on as a replacement early in the second half.
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