In a game where the lead changed hands several times, two converted tries within the space of three minutes around the hour mark from winger Morgan Meaclem and full-back Jacob Lloyd eventually swung the match Merthyr’s way.
Ellis Shipp, Sam Cross, Daniel Phillips, Jack Perkins and Dafydd Thomas also scored for the Ironmen. Outside half Ben Jones converted six of their seven tries to also pass 100 points for the season.
It also meant a losing return to his former club for ex-Merthyr head coach Dale McIntosh – now in charge at Brecon. Centre Tom Richards’ brace along with tries from Andy Nicholl and Jake Newman bagged Brecon a bonus point. James Dixon kicked four conversions and three penalties.
This victory takes Merthyr up into second and above Neath – who are next in action on Boxing Day when Bonymaen visit The Gnoll.
Leaders Pontypridd are now six points clear at the top after a hat-trick from No 8 Joe Miles inspired their 26-17 derby victory over Ystrad Rhondda at Sardis Road. Rob Jones grabbed Ponty’s other try with Jaydan Pugh adding three conversions.
Kurtis Williams, Thomas John and Kelly Jones were the visitors’ try scorers. Rhys Truelove converted Jones’ try.
Reflecting on the win, Miles said: “It was a tough game; we said all week they were going to play off emotion. We knew it was going to be a completely different Ystrad team to what anyone has seen this season – and it was exactly that.
“To be fair they just didn’t stop coming, but we let ourselves down with our discipline. In the end we showed a lot of character to control and we’re showing the characteristics of a top of the table team.
“When things are getting tough, we still manage to bring it around and ultimately it’s still a bonus point win, and we finish for Christmas top of the table. But there’s a lot of lessons from that.”
Meanwhile, after three successive defeats Bargoed returned to winning ways as they were victorious 26-14 against Newbridge. Prop Louis Jones scored twice with Rhys Stephens and Morgan Edwards securing a bonus-point win for Bargoed. Josh Prosser kicked three conversions.
Narberth opened up a five-point cushion between themselves and the bottom two after edging Newcastle Emlyn 18-17. Tries from Harrison Griffiths and Will Blackburn, along with a conversion and two penalties from Jonathan Rogers, won it for the Otters.
Llyr Jones and Steff Evans got the tries for Emlyn, who remain bottom. Shaun Leonard converted both tries and kicked a penalty.
Captain Corey Nicholls, Ralph Miller, Tom Burnham and Rhys Hunt were among the scorers for Cross Keys in a 32-19 win at Cardiff Met. Adam Tetley kicked a pair of conversions while Owain Davies sent over a conversion and two penalties.