Newport Gwent Dragons will be without Wales squad trio Toby Faletau, Lloyd Burns and Lewis Evans for their RaboDirect Pro12 derby at the Scarlets.
All three, as well as Luke Charteris, have been included in Wales' 28-man for the clash with Australia on 3 December.
Replacing them in the squad from their Amlin Challenge Cup win over Perpignan are: Jeavon Grove, Tom Brown and Steve Jones.
The Scarlets are expected to be without all eight of their Wales players.
Scarlets are unbeaten in their last seven matches in all competitions, since their 10-20 reversal in Treviso in the RaboDirect Pro12 on 1 October.
They have won their last four games at Parc y Scarlets, and are undefeated in their last three encounters with fellow Welsh Regions.
The Dragons have begun their European Challenge Cup campaign with back-to-back wins over Prato and Perpignan, but in the Pro12 play have won just one of their last four matches.
They have not won away in this competition since a visit to Aironi on 20 February, but they have won four of their last five encounters with fellow Welsh Regions.
Scarlets have won the last six clashes with Dragons in this tournament, but the Newport based outfit won 26-9 when the two sides met in the LV= Cup at Rodney Parade on 6 February.