Cardiff’s wait for a win over the Scarlets at the Arms Park goes on following a rollercoaster ride of a festive fixture.
They led at the break and then again midway through the second half thanks to touchdowns from wings Mason Grady and Josh Adams.
But, in the end, two tries from former Wales scrum-half Gareth Davies proved decisive as the visitors prevailed despite having three players yellow carded and spending much of the game defending.
So Cardiff, who haven’t beaten the Scarlets at their famous home ground since 2019, had to settle for a losing bonus point from this URC Welsh derby.
They went into the game having made six changes from last weekend’s dramatic Challenge Cup comeback victory over Ulster.
That included an all-new front row, with club captain Liam Belcher having recovered from the neck/shoulder injury he suffered on Wales duty last month, while Taulupe Faletau came on as a replacement after two months out with a knee problem.
The Scarlets welcomed back a raft of Welsh internationals, with the likes of Davies, Blair Murray, Tom Rogers and Ryan Elias coming in, alongside Tongan lock Sam Lousi.
When the game got underway in front of a bumper crowd of 11,728, it was Cardiff who applied all the early pressure and they were to cross the whitewash no fewer than three times in the opening 15 minutes, only to be denied on each occasion.
Flanker James Botham twice had tries ruled out due to knock-ons from team-mates just prior to him touching down, while prop Danny Southworth was held up over the line.
Having spent most of the opening quarter under the cosh, the Scarlets began to come into the game and they were the ones to open the scoring against the general run of play on 23 minutes.
A sustained passage of attacking play in the 22 culminated in centre Eddie James being worked over on the left with Joe Hawkins adding the conversion.
But having taken the lead, the visitors were then reduced to 13 men as they picked up two yellow cards in quick succession – flanker Josh Macloed for a tackle off the ball and scrum-half Davies for a deliberate knock on.
With two players in the bin, there was bound to be space out there and Cardiff swiftly exploited it as long passes from Callum Sheedy and Cam Winnett fed Grady.
The winger still had work to do but he did it well, riding the tackle of the corner-flagging James to get the ball down in the left corner, with Sheedy converting from the touchline.
The hosts continued to apply heavy pressure, but were unable to take further advantage of their numerical superiority, with Alun Lawrence stopped centimetres from the line after a big charge off a lineout and Sheedy smothered by Blair Murray as he looked to utilise an overlap.
In the end, they had to settle for a penalty from Sheedy in the final play to give them a 10-7 lead at the conclusion of a first half they had dominated.
Half-time: 10-7
When play resumed, it was a similar story to what had gone before as Lawrence was held up over the line in the face of determined defence from the Scarlets.
Then, once again, salt was rubbed in the wounds when scrum-half Davies escaped down the touchline for a converted try that gave the visitors the lead.
Cardiff responded immediately as Adams won the race to a Sheedy kick into the right corner after Lawrence had made a big carry in midfield off an attacking lineout.
Sheedy again slotted the conversion from wide to make it 17-14 and that was followed by the arrival of Faletau and fellow back row international Alex Mann off the bench.
But then the game turned again as Gareth Davies produced a trademark interception try, picking off a pass from opposite number Aled Davies at a lineout and sprinting home from some 65 metres, with Hawkins converting.
A further twist soon followed when the Scarlets had a third player yellow carded, with centre Johnny Williams sent to the sin bin for interference from an offside position after a stirring burst by Faletau.
But Cardiff couldn’t capitalise and despite throwing everything into attack in the closing minutes they couldn’t conjure up the decisive score.