Dunvant were denied their first win of the season by a controversial injury-time try for Felinfoel.
The basement Division One West side had lost their previous 21 league matches this season. But they looked certain to break their duck before Luke Marsh touched down to secure a narrow 31-27 victory.
It was scrum-half Marsh's second score of the afternoon but the hosts claimed the ball had not reached the try-line.
Sam Crowley, Mike Arnold and Lee Tucker crossed for Dunvant but Felinfoel had already scored tries through centre Ryan Nicholls, fly-half Stuart Wall and former Dunvant player Simon Delaney.
Second-placed Tonmawr gained a bonus-point 33-10 away win at third-placed Narberth with wing Ryan Davies grabbing a double to assist Hywel Davies, Steve Lewis and Mickey Evans.
Cwmllynfell beat Carmarthen Athletic 34-22 and Whitland and Bonymaen shared the spoils in a 15-15 draw. Carwyn Jones scored all the points for the hosts with tries from Robbie Ford and Duane Eager.
Division One East Champions Blackwood hammered Caerphilly 86-24 thanks to hat-tricks from the James brothers. Both Trevor and David James crossed three times each in an 11-try blitz against the fifth-placed outfit.
Luke Knight added two tries while Mark Birkley and Adam Coupe completing the scoring while the home side scored consolation touch downs through James Walby, Keiran Phillips and fly-half Dan Ellis who claimed 14 points.
It was a try-scoring feast across the three games played in the division with UWIC running in eight tries in their 49-15 romp over Merthyr.
Bargoed moved into fourth place in the table with a convincing 29-15 victory over Rumney. The hosts raced into a 24-5 interval lead with wing Gary Jones grabbing a double along with Rhys Humphreys, Lewis Wayman and Danny Jones.
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