Scarlets head coach Wayne Pivac has made one change to his starting line-up that will tackle Cardiff Blues at Parc y Scarlets on Saturday.
International tighthead prop Samson Lee comes into the starting XV with Peter Edwards moving to the replacements bench.
A home victory would see the Scarlets move a step closer to ensuring qualification for next season's Champions Cup and a step closer to securing a top four finish in the Guinness PRO12.
"There will be a lot of intensity in terms of personal battles for Wales jerseys and some thrilling individual match-ups right across the park. We know they're playing very well and scoring a lot of tries. They're trying to get up the table to qualify for Europe," said Pivac.
"From a team point of view it's definitely one game at a time for us. We're in a position where we can control our destiny."
Meanwhile, record appearance holder Taufa'ao Filise returns to the starting line-up for Cardiff Blues.
Prop Filise, who has clocked up 213 games for Cardiff Blues, is one of two changes made to the starting line-up by head coach Danny Wilson.
Hooker Matthew Rees is also called into the team to face his former region in a must-win encounter for both sides.
A positional change will see Sam Waburton and Ellis Jenkins switch flanks in the back-row.
Dillon Lewis and Kristian Dacey are named among the replacements for the big league clash.
Blaine Scully (hand), Alex Cuthbert (knee), Cory Allen (ankle), Chris Dicomidis (ankle) and Sam Hobbs (shoulder) are all unavailable for selection.
"A top six finish is a challenge for us to get, but with four games to go we have got something big to fight for which maybe in previous seasons hasn’t always happened," said Wilson.
"This game becomes the biggest of our season; to give ourselves the opportunity to carry on with that quest for the top six.
"Every game is simply huge now and we have got to get a victory. We know to win away from home, at one of the toughest places to go in the Guinness PRO12 and get a result, it is going to need to be top drawer display from us."
Form: Scarlets only defeat in the last five rounds of the Guinness PRO12 was 23-24 in Edinburgh on 28th February. A Scarlets victory should ensure their qualification for next season's Champions Cup, keeping their record intact of qualifying for the top tier European competition every year. Cardiff Blues have secured maximum point wins in the last two rounds since their defeat in Glasgow on 6 March. Blues only victory on the road this season in the Guinness PRO12 came on a visit to Dragons in round 10. Blues won 29-27 at BT Sport Cardiff Arms Park in round 11 and have only once before achieved a PRO12 season's double over their western neighbours, in 2009/10.
Scarlets: 15 Michael Collins, 14 Steff Evans, 13 Regan King, 12 Hadleigh Parkes, 11 DTH van der Merwe, 10 Dan Jones, 9 Gareth Davies, 8 Morgan Allen, 7 James Davies, 6 John Barclay, 5 David Bulbring, 4 Jake Ball, 3 Samson Lee, 2 Ken Owens (c), 1 Rob Evans
Replacements: 16 Kirby Myhill, 17 Dylan Evans, 18 Peter Edwards, 19 George Earle, 20 Maselino Paulino, 21 Aled Davies, 22 Aled Thomas, 23 Gareth Owen
Cardiff Blues: 15 Rhys Patchell, 14 Dan Fish, 13 Garyn Smith, 12 Rey Lee-Lo, 11 Tom James, 10 Gareth Anscombe, 9 Lloyd Williams, 8 Josh Navidi, 7 Ellis Jenkins, 6 Sam Warburton, 5 James Down, 4 Josh Turnbull, 3 Taufa'ao Filise, 2 Matthew Rees, 1 Gethin Jenkins (c)
Replacements: 16 Kristian Dacey, 17 Brad Thyer, 18 Dillon Lewis, 19 Jarrad Hoeata, 20 Manoa Vosawai, 21 Lewis Jones, 22 Jarrod Evans, 23 Aled Summerhill
Date: Saturday, April 2
Venue: Parc y Scarlets
Kick-off: 15:00 BST (14:00 GMT)
Referee: Marius Mitrea (FIR, 50th competition game)
Assistant Referees: Wayne Davies, Greg Morgan (both WRU)
TMO: Jon Mason (WRU)