Despite a spirited second half fight-back, Cardiff paid the price for a sloppy opening half hour as they fell to a 28-22 defeat to Scarlets on Saturday.
A bumper crowd turned up at the Arms Park for a second consecutive week, but Scarlets took control with a clinical first half performance.
Dane Blacker, Johnny McNicholl and Jonathan Davies all dotted down in the opening half hour to give the visitors a 19-3 lead.
Taulupe Faletau try on the verge of half time ensure Cardiff remained in the contest, but the hosts failed to truly get firing until the second half.
As Dai Young's side stepped up a gear, tries from Rhys Carré and Josh Adams resulted in a tense and enthralling contest after the break, but the reliable boot of Leigh Halfpenny kept the scoreboard ticking, sealing the win for the hosts.
The Blue and Blacks will now turn their attention to Europe, where they are set to meet Newcastle Falcons and Brive over the next fortnight.
It was a a ferocious start to the encounter at a bitterly cold Arms Park with Jarrod Evans slotting the opening points inside two minutes.
The lead was short-lived however as the Scarlets then surged downfield to earn a penalty of their own. It was taken quickly by Blacker and the former Cardiff academy starlet darted over from close-range. Halfpenny added the extras to give his side a 7-3 lead.
Buoyed by a crowd of more than 10,000, the Blue and Blacks looked dangerous with ball in hand and had the upper hand at the scrum. One surging set-piece saw Cardiff attack with the advantage after a clever Faletau flick from the floor.
Williams released Lane and the wing scorched down the right before firing a pass inside to the scrum-half however he was unable to release his audacious offload.
While the Cardiff scrum seemed on top, the line out miss-fired and that gave the Scarlets easy exits following a period of Blue and Black pressure.
The Scarlets continued to enjoy the better of the opening quarter with Vaea Fifita and Sam Lousi causing problems with their combination of power and ball skills, and Cardiff were dealt a blow when Lopeti Timani was sent to the bin.
The second-row made contact with the head of Steff Evans but replays showed there was a significant drop in height to downgrade to a yellow.
Dwayne Peel’s side continued to enjoy themselves in the wide channels and they claimed a second try on 25 minutes, working an over lap on the left before an acrobatic finish in the corner from Johnny McNicholl.
Rey Lee-Lo and Liam Williams were forced off as Joy Neville consulted with the TMO before awarding the try
Halfpenny was unable to convert from the touchline but his side soon dealt another colossal blow to the Blue and Blacks as they struck in fortuitous circumstances.
Rhys Patchell had made a fine break for the Scarlets but the opportunity appeared lost when McNicholl overcooked his kick ahead. However, the ball, which looked to be going dead bounced horrendously back into play and over the heads of the Cardiff back-three and the Scarlets chasers.
Jonathan Davies was on hand to take advantage of the unlikely bounce and dotted down to the delight of the visiting fans. This time Halfpenny was on target and his side led 19-3.
Cardiff appeared shell-shocked but quickly regathered their composure and finished the half well with Faletau crossing off the back of a dominant scrum on 34 minutes. Evans added the extras to make it 19-10 at the interval.
Halfpenny stretched the visitors lead early in the second-half after a strong Cardiff scrum was penalised but the Blue and Blacks soon responded thanks to a close-range Rhys Carré effort shortly after his opposite number Steff Thomas was shown yellow for a high tackle.
Evans slotted the conversion to breathe further life into his side, who now trailed 22-17 before Halfpenny made it an eight point advantage.
Alarm bells rang for Cardiff when a clever kick through almost put Gareth Davies away but Josh Adams covered across to make a try-scoring tackle he had no right to make.
Moments later the in form wing was on hand to cross for his eighth try in seven games. The platform was built on a succession of carries from the likes of Mason Grady, Seb Davies and Faletau.
With space out wide Ben Thomas dinked a perfect kick-pass to Adams, who collected and crossed in the corner.
The try stretched Adams’ club record for tries scored in consecutive games, in the post-2003 era, to seven matches.
Evans’ conversion dropped agonisingly short of the uprights but the try had brought the Blue and Blacks to within three points and their tails were up.
It was now the home side causing carnage in the wide channels, with Evans pulling the strings, and they were unfortunate not to score after a fine Owen Lane break.
However, despite the hosts' best efforts in the final 10 minutes, Halfpenny continued to chip away at the scoreboard, adding a further penalty to give his side a six-point lead.
Aaron Shingler was sent to the sin bin for a stamp on Ellis Jenkins' hand in the final moments, but Cardiff couldn't take advantage as the Llanelli-based outfit held out for the win.