Unbeaten clubs Maesteg and Llanharan turned aside the challenges of Tredegar and Blackwood respectively with Marc Davies reaching 197 points for the season with Llanharan.
Bonymaen made ground as Anthony Evans notched 17 of their 20-16 win over Brynmawr and Carmarthen Athletic had two Graham Evans tries in a 30-25 beating of Beddau.
A late Gareth Morgan drop shot gave UWIC a 19-16 surprise win at Llangennech and there were runaway wins for Rumney (44-0 at Tondu) and Whitland (57-0 home to Treorchy).
Narberth were helped by 13 points from fly half Gareth James as they defeated Glamorgan Wanderers by 23-3.
Despite drawing 16-all at Rhymney, Abercynon regained the top of the table spot in the East after Merthyr had lost narrowly at unbeaten Fleur de Lys.
Merthyr led 8-5 after a Rhys Miles try and three Grant Davies penalties against a Romilly Barnett try, but Fleur fought back and first Richie Thomas went over, then Darren Cook scored the third and match-winning try - all going unconverted.
Matthew Turner kicked Abercynon ahead at 16-10, but Rhymney wing John Thurston took over the kicking for the Brewers and landed two penalty goals.
Gethin Jenkins scored all the points for Builth Wells in a 11-3 success at Croesyceiliog and Hirwaun scraped home 15-11 at Llantwit Fardre.
In the West it was Dunvant who regained their touch to hold on to the lead as they defeated Newcastle Emlyn 39-10 at Broadacre. Their talented young star Ieuan Evans at scrum half grabbed one of their five tries and wing Simon Jenkins added two tries and 14 points with the boot.
Corus fell badly at Waunarlwydd by 27-13, but Cwmllynfell retained their hard-earned second place after a 18-16 win at Felinfoel. Bridgend Athletic and Tonmawr both jumped forward with good victories - the Athletic defeated Cwmavon
25-16 and Tonmawr worked hard to defeat Cardigan away by 14-5.
Pencoed had tries by Nick Hawkins, Lyndon Griffiths and Gareth Hurley and 15 points by the boot of full back Gareth David as they beat Vardre 30-17, for whom skipper Rob Foley and Nick Walters crossed for tries.
Bryncoch and Maesteg Quins played a match in the South-West that could have a huge bearing on the final count and the Quins came up surprise away winners by 16-14. Andrew Leighton and Ian Morris gained the Quins tries and Robbie Morris
placed two penalties.
The Quins go into second-place though Banwen held on at the top by defeating Seven Sisters 26-13.
In the South-East a Nathan Walters try took Gilfach Goch to a 13-10 win over Mountain Ash, while unbeaten Treherbert keep in front after a 28-13 win at Rhydyfelin. Darren Griffiths and Chris Lee scored two tries each for Treherbert
and Julien Jones and Danny Farr replied for Rhydyfelin.
Senghenydd swept aside Newport HSOB by 36-15 to lead the East with Brynithel, who held off Pontypool Utd 21-6 with tries by Paul Rogers and Jamie Brown. Alyn Ford was the Senghenydd hero with 28 points as he scored a try, conversion, drop goal and six penalty goals.
Kidwelly's 47-24 win over Llandeilo keeps them top in the West with Steve Jones and Phil Middleton notching try hat-tricks. However, an injury to the referee after 49 minutes saw the match between Hendy and Penclawdd abandoned after Hendy led 22-0.
Bargoed and Blaina head the East division in that order after both won, though losers Chepstow and Monmouth respectively, worked hard in away matches. Biggest leap was by Pontllanfraith, whose 20-7 success over Crumlin lifts them after five straight losses.
It was same again in the North, where top club Ruthin beat off battling bottom club Bala 41-13 and Nant Conwy beat a very game Llandudno by 29-0. Rhyl ganed the only away win, by 21-19 at Pwllhelli.
South-West leaders Taibach played and defeated Cefn Cribbwr by 33-8 on Friday night and two matches fell by the wayside without playing, including Alltwen's game at Pyle. It was also Friday night for Aberdare's win against Bedlinog, that was switched to the Aberdare floodlights in the South-East. Fairwater's
ace centre Damian Walsh gained the two penalties that gained them a 6-0 win at
Cefn Coed. Pontycymmer joined Fairwater on 24 points after they won 19-9 away to Dowlais.
In the West, Loughor's 30-13 home win over Neyland kept them in front of Llaneli Wanderers by three points, though the latter battered brave bottom club Bynea by 65-7, running in 11 tries in the process. Llandybie's match at Pembroke Dock was called off, giving Laugharne the chance to go third and they promptly defeated Milford Haven by 34-15.
Colwyn Bay are the only unbeaten side in the North, yet their sixth straight win, by 22-5 over Rhos, leaves them just behind Denbigh, who battered Bangor University by 86-0 to gain a seventh win in eight matches. The scene is set for a meeting with Denbigh on the last day of the season. Cox (2) and Mark Earl scored the vital Bay tries.
Only two matches were played in the East, but bottom-placed clubs Ogmore Vale and Ferndale gained only their second wins of the season in the South-East as Ferndale beat Rhiwbina by two points and Ogmore did a similar trick at Deri.
Cefneithin lead the West after a 30-6 win over Morriston and in the South-West, Resolven remained unbeaten after a win at Porthcawl, while second-placed Abervan Green Stars scored no tries, but just edged home 9-8 at Crynant.