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.
As the countdown continues for RWC2015, Tournament Chief Executive Debbie Jevans visited the Millennium Stadium to discuss preparations for the eight matches and reveal the positive news that 100,000 tickets for games at the home of Welsh rugby have sold in the last seven days.
Jason Harries is targeting a first win on the World Series circuit this season with Wales. The series returns to action this weekend in Dubai where Harries is part of a team hoping to build from its efforts in round one in October.
Wales skipper Jevon Groves says his side have addressed a few points from Gold Coast and aim to 'hit the ground running' in the next two rounds of the World Series, kicking off with this weekend in Dubai before heading off to South Africa next week.
Wales Sevens manager Steff Thomas is hopeful his side can build from a quarter-final spot in the opening round of the World Series in Australia when his side take part in the forthcoming double header in Dubai and South Africa.