Cardiff are back seven points clear at the top of the Championship table.
The Bluebirds beat Blackburn 3 - 0. Fraizer Campbell, Joe Mason and Peter Whittingham scored.
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Any heavy showers will clear away northeastwards through late evening.
The Scarlets were comprehensively beaten 38-16 by Leinster in Dublin.
Cardiff Blues survived an onslaught from Pau's powerful pack to book a place in the European Challenge Cup final.