Cardiff crashed to a 35-20 defeat as the Scarlets ran away with affairs in the United Rugby Championship.
The Blue and Blacks travelled to Llanelli on the back of an impressive comeback victory over Glasgow Warriors and made a promising start.
Jarrod Evans booted his side into the lead and Josh Adams snatched the opening try of the game and they appeared the better team from the opening exchanges.
However, from the moment Sam Costelow responded with an opportunist try, the west Walians dominated, running in three more tries through Johnny McNicholl (2) and Sione Kalamafoni, who was later red carded.
It was a bitterly disappointing performance and result for Dai Young’s side - who did claim a late consolation score through James Botham - and are now set to welcome the Scarlets to the Arms Park in a week’s time, licking their wounds.
Cardiff made a fast and direct start in west Wales and opened the scoring through the boot of Jarrod Evans on four minutes.
Sam Costelow levelled two minutes later but Cardiff controlled the majority of the opening exchanges.
They also enjoyed plenty of possession but the game-breaking moment or final pass was lacking as the Blue and Blacks were initially unable to turn pressure into points.
That was until 14 minutes when good work from Jason Harries, chasing a Tomos Williams box-kick, gave his side a superb attacking opportunity in transition.
He regathered possession after the ball ricocheted off Javan Sebastian and Ben Thomas showed plenty of patience and maturity as he looked for the space and dinked a perfectly weighted kick to the corner for Josh Adams to chase.
The ball bounced high over the try line and Josh Adams had plenty of pace to win the race and dot down on his first appearance since facing Harlequins in January.
Evans added the extras and Cardiff continued to press with Rey Lee-Lo I particular causing the hosts problems on the outside.
The hard work was undone however, when Cardiff kicked loosely and Costelow attacked on the counter against the run of play. He managed to slip out of two tackles as the Blue and Blacks looked to reconnect in defence and he showed plenty of pace to finish the opportunity, which he then converted to level the scores.
The Scarlets fly-half had the opportunity to boot his team into the lead on 25 minutes but pushed his effort wide where as Evans made no mistake moments later.
Evans’ kick gave Cardiff a slender three point advantage but it was soon surrendered in disappointing fashion. Having given away a penalty, the Scarlets kicked to the corner and while their forward charge was rappelled, the ball was spread wide and Johnny McNicholl stood up Jason Harries to score on his 100th appearance for the club.
Costelow was again off target, meaning the Scarlets led by just two points as half-time approached but they turned the screw in the closing stages.
They were twice held up over the line and Dillon Lewis was sent to the sin-bin before Sione Kalamafoni picked up off the back of a dominant scrum and powered over.
Costelow converted and the hosts took a nine-point lead into the break, which Dai Young would have been bitterly disappointed with after watching his side dominate for large periods earlier in the half.
Evans was off target early in the second half and there was soon a long delay after replacement back-row Gwilym Bradley was clattered by a thunderous double tackle.
Play was immediately halted as the medics ran on and following extensive replays, Kalamafoni was sent off having connected with the head of the young flanker.
Following a frantic period of play, with the home support seething, and in which both teams had opportunities, Adams was sent the sin-bin for a deliberate knock on. Had he held onto Jonathan Davies’ pass he would have been in for an intercept try but instead the ball was lost and Costelow slotted another three-points.
Fired up by the perceived injustice and with both teams reduced to 14, the Scarlets dealt a killer blow to Cardiff as McNicholl waltzed inside the defence for his second of the night.
Costelow converted and the Blue and Blacks were now trailing by 19-points and were left with too much to do, despite a late score from Botham.