Judgement Day III: Rivalries set in stone - BBC Cymru Wales' trailer
Watch BBC Cymru Wales' trailer for Judgement Day III as Cardiff Blues prepare to face Ospreys and Newport Gwent Dragons get ready to battle Scarlets in a Pro12 double-header on Saturday, 25 April.
It is the third year running that back-to-back derbies are being staged at the Millennium Stadium.
Blues face Ospreys at 14:30 BST, followed by Dragons against Scarlets at 16:45 BST.
Scrum V on BBC Two Wales and Clwb Rygbi on S4C will have live coverage of both matches.