Simon Easterby's side are guaranteed to finish sixth in the standings as they sit 10 points behind the fifth-placed Ospreys and the same number above the seventh-placed Blues. While the Blues cannot catch the Scarlets despite their fine run of form in recent weeks, they cannot themselves be caught by the Dragons so are in no danger of finishing as the nation's lowest placed region. The Blues could be overtaken by Edinburgh, though, if they lose and the Scottish side earn a shock win at league leaders Leinster.
The Scarlets head into the final week having won three of their last four fixtures, but that solitary defeat came at the hands of the Blues on Easter Sunday. The Blues edged their Judgement Day battle 17-13 in the capital and they have since won away at Connacht to take their victorious run up to four fixtures. It's a stark turnaround for the Blues, who were hammered at the Ospreys back in March but saw off Ulster and Edinburgh prior to winning at the Millennium Stadium and The Sportsground.
But while the Blues are on their best run in the competition since the 2010/11 season, victory at Parc-y-Scarlets would still be something of an upset seeing as they have won just one domestic derby on the road in the past four seasons (they won 16-5 at the Dragons in September 2012) and have only left Llanelli with a league win once since the inception of regional rugby.
"We're keen to leave a decent taste in people's mouths as it's a long old summer when you're on the back of a loss," said Scarlets back row Rob McCusker, whose men had not taken the spoils in a derby this season until the Dragons were downed seven days ago.
"We're keen to leave people in a positive frame of mind at the end of the season - we want people to come back next season. It's also important to give the boys a nice send off and make sure they keep fond memories in their minds.
"We're really disappointed with our form in the derbies - it's not like us and not where we want to be. Saturday is a chance for us to put that right and salvage a win."
Scarlets Head Coach Simon Easterby has made five changes to his starting line-up from the side that secured victory, and European qualification, over Newport Gwent Dragons last Friday evening. Steven Shingler moves from fullback to partner captain Jonathan Davies in the centre with Liam Williams making a return to the fullback berth after a two week ban.
Rhodri Williams is handed a start at scrum half with Gareth Davies moving to the replacements bench. Two changes in the pack see Johan Snyman replace the injured George Earle in the second row with Aaron Shingler coming in to the backrow for John Barclay who has undergone routine surgery on his shoulder.
Simon Easterby said: "The Blues are full of confidence at the moment, they beat us a couple of weeks ago and can't get top 6 but they can spoil the end of the season for us. There's nothing worse than playing 80 minutes of rugby and not being able to do anything about it for 3 months. We really have to buy in to getting a performance this Saturday."
Wingers Alex Cuthbert and Harry Robinson will both play their 50th game for the Cardiff Blues as the visitors hunt a fifth successive league victory to finish the campaign in style.
Coaching duo Dale McIntosh and Paul John make a number of changes to the side that claimed a hard-fought victory over Connacht Rugby last time out.
Centre Isaia Tuifua comes into the starting line-up for the derby clash while there is also a start for fly half Simon Humberstone with Gareth Davies missing the game through injury.
Robin Copeland will make his last appearance for the Blues at eight while Lewis Jones starts at scrum half as Lloyd Williams moves to the bench.
Coach Paul John said: "The confidence we have picked up in recent weeks has helped us. That showed against Connacht in the manner in which we fought back to get the win and we want to keep that going now until the final match."
The Blues will certainly be confident of the 'double' that McCusker mentions given the way they have responded since Paul John and Dale McIntosh took over the reins from Phil Davies in March. John has understandably been delighted with what he's seen from his troops in recent weeks and he believes the belief that has been built up over the past two months or so will stand them in good stead against the Scarlets.