Luke Richards added the conversion and penalty but Llanelli had to come from behind after trhe second-placed Wizards led 16-10 at the break through Richard Thomas and Jamie Davies.
Matthew Jacobs and Craig Shingler scored the tries that kept Stradey Park on song.
Neath motored into second place with an emphatic 62-20 win over Cross keys thanks to a second half rout at the Gnoll.
Newport romped to to a ten-try win over lowly Llandovery. Newport Gwent Dragons youngsters Jason Tovey and Gethin Robinson weighed in with tries as the Black and Ambers cruised to a 67-5 win at Rodney Parade.
Swansea failed to build on a promising first half and missed out on a bonus point in a 23-15 win over Bedwas.
Wales Sevens ace Jason Lewis brought Pontypridd crashing at Ebbw Vale, 13-3, and Geraint O'Driscoll's 26-point haul was not enough to save Pontypool from a 42-31 loss at Glamorgan Wanderers.