With Nick Walne unavailable due to a knee injury, Rhys Williams switches to right wing and Nick Robinson fills the vacancy at full back.
Williams (7) and fellow wing Craig Morgan (10) are Cardiff's top try scorers so far this season. Iestyn Harris heads the points-scoring list with 167 to his name. Seven of the team - Rhys and Martyn Williams, Jamie Robinson, Pieter Muller, Iestyn Harris, Emyr Lewis and Craig Morgan - played in last year's semi-final against Pontypridd.
Coach David Young said:
"We have picked the strongest available team. Nick Walne is having a scan on his knee but expects to be available again within a fortnight. Unfortunately hooker Greg Woods has sustained another neck injury and will not play again this season. There is no tougher task than playing Llanelli in a cup semi-final but we have picked up a couple of good results recently and are looking forward to the challenge."
Other players continuing to be unavailable because of illness or injury are Rob Appleyard, Dan Baugh, Spencer John, Adam Jones, Andrew Lewis, Dan McShane, Gary Powell and Anthony Sullivan.
Cardiff: N Robinson; R Williams, J Robinson, P Muller, C Morgan; I Harris, R Powell; K Fourie, P Rogers, B Evans, H Senekal, J Tait, R Sowden-Taylor, M Williams (capt), E Lewis.
Replacements: J Yapp, L Collins, L Tait, J Brownrigg, R Smith, M Allen, D Dewdney.
Llanelli: B Davies; M Jones, M Watkins, L Davies, G Evans; S Jones, G Easterby; I Thomas, R McBryde, J Davies, V Cooper, C Wyatt, D Hodges, S Easterby, S Quinnell.
Replacements: M Madden, A Gravelle, L Gross, I Boobyer, M Phillips, G Bowen, S Finau.