The Scarlets produced a stunning defensive performance to beat Cardiff 25-19 in the capital and claim their first United Rugby Championship win of the season.
Gareth Davies scored two tries for the second successive season at the Arms Park as the Scarlets recorded their fifth successive win at that stadium.
A pair of Ioan Lloyd penalties gave the Scarlets an early 6-0 lead, but Harri Millard’s converted goal gave Cardiff the upper hand in a messy opening.
Davies had a number of tries either side of Millard’s second before Johnny Williams crossed for the Scarlets.
Cardiff were awarded a penalty but failed to capitalize on the Scarlets’ advantage of having 13 men for nearly 10 minutes as the visitors held on valiantly.
The Scarlets, who had won just once away since December last year, took the lead through Lloyd’s penalty kick in the 8th minute of the first half.
The visitors were reduced to 14 men shortly after Sam Lousi was shown a yellow card for Efan Daniel by referee Craig Evans, but extended their lead with another penalty from Lloyd.
Cardiff went ahead in the 22nd minute when Millard went under the post after a fantastic offload from Dan Thomas and Tinus de Beer added a further strike.
The Scarlets responded with a try of their own 10 minutes later, with Davies pounced after Lloyd and Marnus van der Merwe had brought the team within a few meters of the line.
Lloyd missed the conversion on his eighth attempt this season to end his 100% off-the-tee record.
Millard claimed his second try of the game on a red clock, diving into a corner after sustained pressure from Cardiff, despite Callum Sheedy missing his kick.
The Scarlets went back into the lead six minutes into the second half, with Davies scoring his second try after a fine score from Lloyd, who added the striker to put his side 18-12 ahead.
The third try came for the visitors just as Williams was racing under the posts and Lloyd made no mistake with the conversion.
However, the match appeared to have been turned on its head as the Scarlets received two yellow cards in a matter of minutes.
Tom Rogers was guilty of an intentional knock and Cardiff took the advantage immediately when a penalty try was awarded, with Josh Macleod also forced to sit out for 10 minutes.
Blair Murray produced a superb attempt-saving tackle on Gabe Hamer-Webb as the Scarlets held on.
