Scarlets sit top of Pro14 Conference B after edging out Blues in a full-blooded Welsh derby at the Arms Park.
Leigh Halfpenny was on deadly form from the kicking tee, slotting three penalties and a conversion. Those 11 points - plus a trademark interception from Halfpenny's Wales team mate Gareth Davies - was enough to see the West Wales region keep their noses ahead in front of a packed Arms Park crowd.
For the Blues, Wales star Josh Adams continued his impressive run of form with an outstanding try, with fellow winger Owen Lane also weighing in with a score.
Scarlets took an early lead courtesy of two Halfpenny penalties, but when Owen Lane chipped ahead following a pass from Hallam Amos, the Wales prospect showed the speed to chase his own kick and score the game's first try.
Outside-half Jarrod Evans converted, only to slip up moments later when his pass was picked off by Davies, the Scarlets scrum half with the speed and side-stepping ability to take the opportunity.
Another Halfpenny penalty made it 16-7, but after the break the Blues had chances to win the game. Adams swapped passes with centre Ray Lee-Lo in a sweeping move, culminating in a memorable try for Wales' World Cup record try scorer.
But despite replacement Jason Tovey's conversion and some late pressure, Blues weren't quite able to overhaul Scarlets' lead.