Unbeaten Llantwit Fardre and Abercynon remain in close proximity after wracking up third wins in a row.
Fardre dug deep to beat Llantrisant 19-15 at Cae Fardre thanks to tries from Keiran Evans, Geraint Jones and Dan Holby while Matthew Turner inspired Abercynon to beat Newport Saracens with a 14-point haul in their 24-10 win.
Rhymney won the derby at Fleur De Lys to condemn the home team to their first defeat of the season in Division Three.
Wing Greg Plant sped over while fly-half Steve Lang added the conversion and two penalties before Josh Ferry stepped off the replacement's bench to settle the Rhymney Valley clash. Scrum-half Darryl Cook went over for Fleur.
Passions were also running high in Cardiff where arch rivals Llandaff and Llandaff North squared up. Two tries apiece from Stuart McIntyre and Daniel French clinched the local bragging rights for visitors North, winning 26-20.
Talywain hammered Machen 40-3 in a seven-try rout in Division Four.