The Irish provinces have Stephen's Day off ahead of their derbies in the RaboDirect Pro12, meaning Ospreys have a chance to move up to second in the table.
Ospreys came from behind to beat Scarlets 10 - 6 thanks to an Ian Evans try with five minutes to go.
There are three personel changes for Connacht for tomorrow's clash with Munster in Thomond Park.
Frank Murphy starts at scrum-half for his 100th cap.
Fionn Carr is on the right wing, while Andrew Browne comes in at blindside flanker.
Rob Penney has made wholesale changes to his Munster line-up, with only JJ Hanrahan retaining his place from the win over Scarlets.
James Coughlan captains the side in the back-row, while Felix Jones is at full-back and Keith Earls is on the wing.
Niall Scannell makes his first start in the front-row.
Main image: JJ Hanrahan ©Inpho/Billy Stickland