Cardiff held on for a hard-fought victory over the Scarlets in a tense BKT United Rugby Championship derby in west Wales.
Following a scrappy start to the encounter, in which the Scarlets controlled much of the territory, Cardiff took the lead thanks to an Evans penalty on seven minutes.
A Tomos Williams try gave the visitors further foothold heading into the break, while the boot of Evans remained reliable throughout.
Scarlets set up a nervy finale after Johnny McNicholl's late score, but a red card to Fifita took the spark out of the hosts in the closing stages.
Cardiff will host rivals Dragons at Cardiff Arms Park in the hunt for consecutive derby victories.
Theo Cabango made good ground on the left and while the ball was spread to the right with Halaholo and Lee-Lo combining well, play was brought back for the penalty and Evans gave his side the 0-3 lead.
Minutes later however, the Blue and Blacks were dealt a blow when Lee-Lo was helped off following a heavy collision.
The Scarlets did threaten and they spent long periods in the Cardiff 22. On one occasion a home try appeared inevitable before Faletau demonstrated his ability over the ball to claim a fine turnover, which allowed Priestland to clear.
Leigh Halfpenny responded for the hosts but having weathered the Scarlets storm, Cardiff soon claimed the game’s opening try in stunning fashion.
The likes of Faletau and Lopeti Timani sent the Blue and Blacks surging forwards before Rhys Carré burst through the Scarlets defence and sent Tomos Williams through. Evans converted to give Cardiff a 3-10 lead.
It was a seven-point advantage the they held onto and took into the break despite an onslaught from the Scarlets.
First the home side saw a Corey Baldwin try ruled out after replays showed a long Sam Costelow pass had drifted forward. Halfpenny also struck the uprights as Cardiff survived and the Llanelli crowd became increasingly frustrated.
Evans booted the scoreboard back into action just minutes into the second-half and the Blue and Blacks continue to frustrate the home side with their tenacity.
The fly-half added another penalty on 52 minutes but that was to be his last action as he soon limped off.
It forced a reshuffle of the back-line with Priestland moving to 10 and Jason Harries slotting in at full-back with Mason Grady introduced to the wing.
The Scarlets continued to dominate territory and possession and they piled on the pressure for long periods in the second-half.
Halfpenny appeared odds on to score as the final quarter approached but some fine defensive work from Harries and Tomos Williams ensured he was unable to get the ball down.
The home side remained camped in Cardiff’s twenty-two and they received a significant boost when Kirby Myhill was sent to the sin-bin.
They kicked to the corner and spent countless phases hammering at the Cardiff line, ignoring a potential overlap out wide. When they did finally go through the hands, possession was spilt and Young’s side were handed a reprieve.
From the ensuing scum, the Scarlets, who had recently introduced Lions duo Wyn Evans and Ken Owens, forced a penalty. They opted for the set-piece and spread the ball wide to Jonny McNicholl, who took advantage of Kirby Myhill’s absence during the yellow card period.
Halfpenny converted from the touchline to make it 10-16 with seven minutes left to play.
Scarlets were camped back in Cardiff's 22 almost immediately, in the hunt for the decisive, dramatic score. As quickly as the Blue and Blacks were restored to 15 men, Theo Cabango was sent to the sin bin.
However, in the aftermath, the replays showed a high shot on Shane Lewis-Hughes and Vaea Fifita was sent his marching orders - a red card which took momentum out of the hosts as Cardiff came away with the four points ahead of next week's home clash against Dragons RFC.