Scarlets name European side
Stephen Jones returns to flyhalf with Ceiron Thomas moving back to full-back while Regan King moves to outside centre to allow Gavin Evans to return to inside centre, with Matthew Watkins making way.
There are four changes in the pack with Iestyn Thomas coming in for Phil John at loosehead and Craig Dunlea replaces Deacon Manu on the tighthead.
In the backrow Gavin Thomas replaces James Bater which forces captain Simon Easterby back to the blindside while in the second row Vernon Cooper comes in for Adam Jones.
Scarlets (v London Irish): 15 Ceiron Thomas 14 Dafydd James 13 Regan King 12 Gavin Evans 11 Mark Jones 10 Stephen Jones 9 Dwayne Peel; 1 Iestyn Thomas 2 Matthew Rees 3 Craig Dunlea 4 Vernon Cooper 5 Inoke Afeaki 6 Simon Easterby ( capt) 7 Gavin Thomas 8 Alix Popham.
Replacements: Aled Gravelle, Deacon Manu, Adam Jones, Nathan Thomas, Clive Stuart-Smith, Darren Daniel, Barry Davies