Two tries from No.8 Rob Hills made all the difference in a tense and tightly fought encounter which went to the home side by three tries to one.
Corus were the only side to beat Ton in their inexorable march to the Division 2 West crown last season, but the steelmen have found it difficult to compete at the higher level this term.
While Tonmawr have swept all before them, making it six out of six against the champions, Corus find themselves propping up the table with an imperfect six out of six defeats following a 27-8 reverse at Carmarthen Quins.
The Quins picked up a bonus point to move closer to the league leaders and it proved to be a red letter day for back row man Andrew Thomas. He marked his 100th appearance for the club with his side’s fourth and final try.
Narberth jumped ahead of Bonymaen into third place courtesy of their local derby triumph over Whitland. The home side were leading 7-6 until three minutes to go thanks to a Randall Williams try and Emyr Williams conversion. But then Narberth found a hero in Aled Davies, who added a superb match-winning drop goal to his two earlier penalties to steal the spoils.
Merthyr’s Adrian Jones was another match winner as he scored all his side’s points in a 11-5 win at Dunvant. There was another narrow win for the away side at Bridgend Athletic, where Waunarlwydd fullback Jonathan Lewis conjured up 16 points in a 21-19 victory.
Llangennech moved up to fourth with a comprehensive 29-8 home win over Cwmllynfell. Two tries from centre Nick Reynolds set his side on the road to victory and Adrian Thomas kicked 14 points.
