Former internationals Brett Sinkinson and Mark Jones are brought into the Neath pack with backs coach Pat Horgan in at scrum half, while Newport are yet to name their lineup for this first versus second meeting.
Caerphilly have Stuart Thomas at fly half for their short trip to Cardiff, on an Arms Park pitch that his father graced as a Blue and Black winger.
Cardiff bring in four former Under-21 caps to their park, but it is Caerphilly who are favourites despite having a 0-10 league record against Cardiff.
Swansea and Cross Keys are the clubs most likely to bring up the highest aggregate score of the day, as coaches Tony Clement and Dai Rees are former backs who believe in running rugby, while of the other matches, Pontypridd will be a threat at third-placed Aberavon.
The match between Llanelli and Newbridge is off, due to injuries with the Newbridge props and hookers.