Pontypridd winger Owen Williams goes over in the corner against Cardiff.
Llanelli threw away a massive lead for the second weekend in a row before crashing to a 28-26 home defeat at the hands of Neath in the Principality Premiership.
The previous weekend the west Wales side had been 29 points clear at Aberavon before ending with only a share of the pints in a 32-32 draw.
But this time they squandered a 21 point advantage shortly after the break at Parc y Scarlets before not only conceding victory to Neath, but also a try bonus.
The yellow card received by lock Adam Powell 15 minutes into the second half proved crucial and the visitors ran in two tries before striking through Kevin James for the vital, match winning fourth.
The five point raid in the west by Neath means they move up the table into second, just three points behind league leaders Pontypridd. Paul John's Sardis Road outfit knew they had to win against Cardiff to stay on top and the boot of outside half Dean Gunter did the damage for them.
He kicked four penalties in the first half and another after the break to secure victory. Wing Owen Williams grabbed the visitor's only try, while Rhys Shellard and Matthew Veater crossed for the home side.
Both teams had a player sent to the sin bin and the game ended with passive scrums after Cardiff suffered front row injuries.
Swansea sailed into a 20-0 interval lead at Glamorgan Wanderers before eventually grabbing a try bonus in a 28-12 triumph. With a game in hand on the Pontypridd and Neath, they could climb back to the top when they make up their fixtures.
David Watts, Leigh Bevan, Luke Jones and Rhodri Wells crossed for the visitors and James Dixon kicked two penalties and a conversion. The home side nabbed two tries in the final five minutes to add some respectability to the scoreline, Charlie Johnson and Dan Fish getting the scores.
Premiership new boys Carmarthen Quins took a giant step away from the relegation zone as they ran winless Pontypool ragged to pick up a bonus point in a 40-10 away win. Scarlets wing Darren Daniel enjoyed his visit to Pontypool Park as he zipped over for a hat trick of tries.
Richard Carter and Ellis Lloyd scored the other two tries for the visitors and Gareth Cull added 15 points with the boot. Steve Taylor scored Pontypool's sole try and, to make matters worse, they had No 8 Sam Pailor sent off for punching.
Ebbw Vale must have been thinking about notching a second win when they went into the interval at home against Llandovery 16-10 in front. But in the end the Steelmen fell to a disappointing 24-22. Gareth Bowen kicked 17 points for the home side, but two tries from Wales Sevens wing Ifan Evans, and a third from centre Joe Ajuna, secured the points for the visitors.
A late Dan Davies try earned Aberavon a bonus point at home against Newport, but they conceded three in a 27-20 defeat. Cross Keys had tries from Rob Nash and Will Johnson to thank for their 20-13 home triumph over Bedwas.
Whenever Bedlinog tackle Penallta a massive fixure is guaranteed but this Sunday there will be even more emphasis placed on the two rivals when they contest the SSE Swalec Plate final at Principality Stadium.
Ahead of their SSE SWALEC Bowl Final clash with Taffs Well at Principality Stadium on Sunday, Burry Port share their #FABXV nomination with WRUTV in the search for Welsh rugby's greatest volunteers. Everyone can get involved by sending nominations via twitter to @WRU_Community using the hashtag #FABXV
Cardiff Blues prop Gethin Jenkins and Ospreys centre Ben John look ahead to the first game at Principality Stadium in Saturday's double header which is promising to be a special occasion for all Welsh fans.
Carmarthen Quins Director of Rugby Ian Jones and committee member Jeff Thomas along with Llandovery chairman Handel Davies look ahead to Sunday's SSE SWALEC Cup showdown where both teams are out to prove 'West is best'
SWALEC ambassador Shane WIlliams is looking forward to Sunday's Finals Day where the Cup, Bowl and Plate offers a great opportunity for players and teams to experience the magic of playing at Principality Stadium
Carmarthen Quins coach Richard Kelly believes it is an exciting time to be part of the Scarlets region as his side take on local rivals Llandovery in the SSE Swalec Cup final on Sunday, as WRU TV's Graeme Gillespie discovers