However, victory tomorrow night would throw wide open the race for the title with the Ospreys likely to claim victory in the other game, against the Dragons at Aberavon's Talbot Athletic Ground.
The Dragons are the only side yet to register a win although their performance in defeat against the Blues last time out was encouraging to say the least. Coaches Jason Forster and Gareth Baber will be looking for the same progress tomorrow night although with home advantage and with a victory over the Dragons already this season, the Ospreys will start as favourites.
Blues v Scarlets (Pontypridd 7.15)
Ospreys v Dragons (Aberavon, 7.15)