The Ironmen had lost in their last league outing at Barged on 5 March and then seen Swansea overtake them with their victory at Tata Steel. But three tries at third-placed Pooler saw them triumph 33-13 to move two points clear at the top with five games left to play.
It was a second defeat in a row for Pontypool against teams in the top five chasing the four promotion places following their 25-11 loss in North Wales against RGC. Scrum half Rhys Downes crossed for the first Merthyr try as they built up a 13-3 interval lead.
Pontypool prop Jamie Jeune gave the home side hope when he crossed early in the second half, but further tries from flanker Osian Davies and former Cardiff Blues lock Miles Normandale sealed the win for Merthyr as Matthew Jarvis weighed-in with 18 points with his boot.
RGC 1404 hammered winless Llanharan 80-0 to close the gap on third-placed Pooler to three points with a game in hand. The two clubs are due to meet at Pontypool Park on the final day of the regular season.
The North Walians scored 40 points in each half to inflict another heavy defeat on their hosts following their 93-0 triumph in the SSE Swalec Cup at Parc Eirias. The two teams are due to meet again in Colwyn Bay on 16 April.
Tiaan Loots opened the floodgates, before Will Bryan and former Wales Under 20 cap Afon Bashaw crossed for first-half doubles. Kelvin Davies also got in on the act in the first-half before Sam Jones, Kevin Lang, Richard Hopkins, Danny Cross and Cam Davies completed the 11-try rout after the break.
Reigning champions Bargoed cruised to a 24-0 defeat of Cardiff Met to stay in the top four hunt. Skipper Leigh Meades led the charge with a try, before powerful No 8 Ross Coombes crashed over.
Second half tries from prop Kieran Brown and outside half Matthew Hurley secured the bonus-point to cut the gap between themselves and fourth-placed RGC to three points. As with the North Walians, they also have a game in hand on Pontypool and two on the top two sides.
Newcastle Emlyn clung onto a 13-8 half-time lead to claim a 20-15 triumph over Narberth in the West Wales derby.
