The Blues, who will be looking to build on a 22-17 victory over London Wasps in their opening fixture of the competition last week, have made two changes in the backs with Harry Robinson returning on the wing and Rob Lewis getting the nod at scrum-half.
Up front, Andries Pretorius comes in at No 8 to captain the team and is joined in the back row by Thomas Young who starts at openside flanker.
Scarlets head coach Simon Easterby has opted for a blend of youth and experience as he looks to try and bounce back from last weekend's 34-18 defeat at Worcester.
Gareth Maule and Gareth Owen will combine in the centres, while Dan Newton returns from injury to start at fly-half.
New Australian second-rower Jake Ball will make his second start for the club, while Wales U20 stars Kirby Myhill and Samson Lee come into the front row.
Kick-off is at 6.30pm.
Cardiff Blues: Dan Fish, Harry Robinson, Owen Williams, Gavin Evans, Tom James, Gareth Davies, Robert Lewis; Andries Pretorius, Thomas Young, Luke Hamilton, James Down, Macauley Cook, Ryan Harford, Marc Breeze, Sam Hobbs.
Replacements: Rhys Williams, Campese Mafu'u, Foa Filise, Cory Hill, Rory Watts-Jones, Lloyd Williams, Ceri Sweeney, Rhys Patchell.
Scarlets: Liam Williams, Kristian Phillips, Gareth Maule, Gareth Owen, Andy Fenby, Dan Newton, Rhodri Williams, Shaun Hopkins, Kirby Myhill, Samson Lee, Jake Ball, Johan Snyman, Craig Price, Johnathan Edwards (capt), Kieran Murphy.
Replacements: Emyr Phillips, Phil John, Jacobie Adriaanse, Joel Galley, Dan Thomas, Gareth Davies, Aled Thomas, Nick Reynolds.
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