The five-try rout was the third meeting between the two clubs inside a month and there may be a fourth - if Pontypridd beat Llandovery next Monday.
The Welsh All Blacks led 10-nil at half time courtesy of a splendid 75-yard dash by flanker Steve Tandy who made light of Neath being temporarily reduced to 13-men to race away and touch down for a try that was converted from the touchline by captain Arwel Thomas who then kicked a penalty.
In the second-half, Ponty hit back with a penalty by outside-half Dean Gunter but Tandy increased Neath's advantage with another try from a touchline sprint after a quickly taken lineout.
A thrilling interception effort by Kristian Phillips produced try number three and the Premiership's leading scorer added a second to go with a short-range effort from outside-half Gareth McCarthy whose two conversions completed the scoring.
Principality Premiership Play-Off scores
Neath 34-3 Pontypridd
Aberavon 18-35 Llandovery
Swansea 60-19 Newport