The Welsh All Blacks overcame a 30-minutes delay at the start of the second half as the generator ran out of diesel causing a floodlight failure and the home side themselves ran out of energy against an unrelenting wave of Neath forwards surges.
The Gnoll forwards created two pushover scores as they dominated the scrummage while locks Gavin Evans and Lee Bassett secured a plentiful supply of possession at the line-outs. The fact that the visitors failed to convert possession into points had more to do with some generous refereeing of the offside rule as the visitors found limited space in midfield.
Number eight Gareth Williams opened the scoring rounding off a flowing Ponty attack with an unconverted try, while Neath replied almost immediately as scrum half Gareth James collected his first try of the evening benefitting from a superb scrummage lead by the Neath front row trio of Paul James, Adam Matthews and Adam Jones.
Fly half Mike Thomas restored the home sides lead only for Dylan Pugh to level the scores midway through the first half. Any signs of a repeat half century of points performance as shown against Swansea in the previous round were not visible at Sardis Road even before the temporary gloom as Neath fell behind to a 15pts to 8 after Thomas scored a converted try at the posts.
After a hurried visit to the local garage and lights restored, Neath firstly levelled the scores after prop Paul James capitalised fully on the sinbinning of Thomas to crash over for a try.
While Ponty had their moments, the visitors took the lead for the first time in the match as scrum half James collected his second try at the base of another rapidly advancing Neath scrum. Pugh, growing in statue as the season progresses, added both conversions.
Left wing James Watkins seized on a Neath defensive error to score wide out and while the try went unconverted with Thomas missing all his second half attempts at goal, Pugh settled the visitors nerves with his second penalty of the evening to set up a final against the winners of friday evenings clash between Cardiff and Llanelli.
Meet the members of the WRU's inaugural Youth Board - after an online selection process which saw a host of high calibre candidates submit video applications the WRU has made its first 15 appointments.The board is made up of individuals aged between 16 and 21, and will meet for the first time at Principality Stadium on Monday 15th February.
The Wales Women's team headed to Dare Valley Country Park on a team bonding exercise as the entire squad got together for the very first time in preparation for this season's Six Nations championship which kicks off on Saturday with a clash against defending champions Ireland, in Donnybrook.
Wales Head Coach Warren Gatland discusses his team selection for the opening round of the RBS 6 Nations where he leads his side against Ireland, on Sunday. As WRU TV's Luke Brodley discovers, Gatland is fully aware of the challenges the defending champions pose