Merthyr survived a late onslaught to beat Rhiwbina 29-26 and take home the Swalec Plate at the Millennium Stadium.
A brace of tries from Owen Morgan and further scores from Josh Flye, Osian Davies and Gareth Way sealed a league and cup double for the Ironmen.
Rhiwbina got off to a flying start with tries Brett Chatwin and Sion Summers, but were out-muscled by the Division 1 East champions.
Louis Millar and Chatwin scored late tries to pull the Squirrels back to within three, but Merthyr survived a late scare to take home the Plate.
Rhiwbina stormed into the lead after a well-worked try from wing Chatwin. Outside-half Josh Davies executed a pinpoint cross-kick which found Chatwin, and the Squirrels flyer was too quick for the covering Merthyr defence.
The underdogs stretched their lead after 17 minutes with another score out-wide. The Rhiwbina backs spread the ball to the right flank and Chris Fido offloaded back inside for onrushing full-back Summers to crash over - Gareth McCarthy added the extras.
The Ironmen replied just moments later through full-back Fyle.
The Merthyr forwards tried to shove there way over before releasing the backs who pushed the ball to Fyle.
The full-back dummied his way through the scrambling Rhiwbina defence and touched down to pull his side back to within seven points.
Flanker Davies then found a gap in the opposition defence to complete Merthyr's 12 point comeback.
The back-rower darted through a hole in Cardiff side's defence to score from 10 metres out, fly-half Steve Lang added the extra two points to draw his team level on half-time.
Merthyr, who are a division above their Plate rivals, took the lead after 47 minutes.
The pressure finally told when Morgan squeezed in at the corner following Luke Harwood's offload, taking the score to 17-12.
Morgan scored his second soon after, the lightning winger rounded his opposite man and dived over in the same corner.
Way then crashed over for Merthyr's fifth try to seal the win.
Millar and Chatwin scored late tries to take their team to within three points, but they couldn't get over the line for the winning score.
Cardiff Blues U18 Girls will go into Sunday's Gemau Cymru with an extra spring in their step after Welsh internationals Elinor Snowsill and Philippa Tuttiett offered some last minute tips at a training session earlier this week.
Rob Howley and Josh Lewsey addressed more than 250 community club coaches and referees at the first WRU National Community Conference on the weekend. The volunteers benefitted from coaching masterclasses and workshops in a bid to connect all levels of the rugby pathway in Wales.
The winners of a filmmaking competition organised by the education charity Into Film and the WRU enjoyed a behind the scenes tour of the Millennium Stadium - and a chance to be photographed with the WRU's fire-breathing, rugby loving mascot, Scorch The Dragon, and Welsh international, Jake Ball.
Ebbw Vale coach Jason Strange is proud of his side's effort in against Pontypridd in the Principality Premiership final and as WRU TV's Liz Jones finds out, he's now looking forward to Wales' Under 20 campaign with confidence.
The countdown to the Junior World Championships starts in this week's Principality Welsh Rugby Union Podcast. We speak to WRU U20 coaching co-ordinator Allan Lewis and captain Rory Thornton. We speak to the winning teams at SWALEC Finals Day, Wales Sevens manager Steffan Thomas and Wales women's rugby manager Caroline Spanton.
We hear from JPR Williams, Tommy David and all six clubs in SWALEC Finals Day, as well as the first woman to referee a game at the Millennium Stadium, in this week's Principality Welsh Rugby Union Podcast. JPR and David reminisce over the 1979 final, while we hear from Pontypridd, Bridgend, Ystrad Rhondda, Ystradgynlais, Cambrian Welfare and Newcastle Emlyn. Kath Pritchard became the forst Welsh woman to referee a game at the Millennium Stadium - we speak to her and WRU community referee development officer Paul Adams.
All roads lead to Cardiff on Sunday for the SSE SWALEC Finals Day at the Millennium Stadium. Cambrian Welfare tackle Ystradgynlais in the Bowl final, Ystrad Rhondda play Newcastle Emlyn in the Plate final while defending champions Pontypridd face Bridgend in the Cup final.
A look ahead to Judgement Day and back at youth finals day in the Principality Welsh Rugby Union Podcast. We hear from Andrew Coombs, Jake Ball, James Davies, Dan Lydiate and Josh Navidi. We also speak to Wattstown, Ystradgynlais, Rhydfelin, Pontypool United, Penallta and Pontypridd youth coaches at finals day at the Millennium Stadium.
Ystradgynlais and Ynysddu played out a titanic struggle at Taffs Well in the SSE SWALEC Bowl semi-final. At the end of the game neither team could be separated after a 15-15 stalemate but Ystradgynlais go through on try count.
Wales Under 18 captain Calum Haggett has received a conditional offer to read Biomedical Science at St Anne's College, Oxford. WRU chairman Gareth Davies went to meet Calum and Coleg y Cymoedd Principal Judith Evans to wish him luck in his exams and pass on some of his personal experience.
WRU National Academy Coaching manager Allan Lewis will retire, a new Elite Coach Development Manager post has been created and WRU international skills coach Jason Strange will now fulfil his WRU role on a full time basis.
Developing the game in Wales and creating a stable and progressive environment for players of the future
Taking the grass roots game out across the length and breadth of the nation, the SWALEC Leagues are the focus of the community rugby in Wales
SSE SWALEC Cup
The SSE SWALEC Cup, Plate and Bowl continue the legacy of the WRU Challenge Cup, culminating in a shot at glory at the Millennium Stadium
Women's Community Rugby embraces both the regional and community club game from Girls' Leagues through to the Women's Premier Division