Llanelli put in a competent display in windy conditions as they ended up convincing 37-5 winners.
The omens for the visitors were not promising as straight from kick-off they were penalised for slipping the bind at a scrum. Outside half Williams slotted the kick to give Llanelli a 3-0 lead.
Neath started to gain some possession but, as with the Llandovery game on Saturday, they were the architects of their own downfall with handling errors and ill-discipline again blotting their copybook throughout.
The first try came the way of the home side soon enough when the ball was chipped through by a Llanelli boot for Kyle Evans to cross near the posts. With Williams adding the conversion, Llanelli led 10-0 after 15 minutes.
Llanelli had another chance to extend the lead halfway into the first half but Williams missed a second shot at goal. The impressive outside-half had a chance to redeem himself five minutes later though and when Neath were penalised for diving on the ball, the youngster duly slotted the kick to make it 13-0 to the home team.
Things got worse for Neath five minutes later as flanker Tom Morgan picked up his second yellow card in two games, this time for handling the ball on the floor.
Williams was again successful with a 35 metre penalty and the Welsh All Blacks’ first-half misery was complete when the outstanding Williams chipped through the static Neath defence for Justin James to collect and dab down. Williams again converted to give the home side a 23-0 cushion at the break.
Williams added another converted try early in the second-half when he strolled through a yawning gap to score and make the score 30-0 to the home side, effectively ending the game as a contest.
Ten minutes later, Neath were again reduced to 14 men when Rhys Jones was penalised for using his hands on the floor but this did not stop the Blacks getting on the board themselves when Jason Howells collected the ball five metres out and fed Kevin James, who took two defenders over with him to get Neath off the mark for the evening.
Llanelli claimed a well-deserved bonus point though when the home side spun the ball through some quick hands for Dylan Morgans to score under the posts.
Williams added the conversion to finish off what was a top quality performance both from himself and his side.