Newport Gwent Dragons and the Scarlets will launch Saturday's action, followed by Cardiff Blues facing the Ospreys. More than 30,000 tickets have so far been sold for an event billed as 'Judgement Day' by the Welsh Rugby Union.
And it will see several of Wales' RBS 6 Nations title-winning stars back in action just a fortnight after the record-breaking 30-3 victory over England secured silverware and denied their arch-rivals a first Grand Slam since 2003.
Among several intriguing head-to-head contests is the battle between rival openside flankers - but Wales back-row colleagues - Sam Warburton and the Ospreys' Justin Tipuric.
"This is a big occasion, one that we are looking forward to," Blues rugby director Phil Davies said. "We will be playing at an iconic venue and trying to keep the feelgood factor of Welsh rugby going."
Dragons boss Darren Edwards played in the Premiership's London double-header when he was with London Irish, and he hopes to see the Welsh version make its mark.
"I think it is a fantastic concept," Edwards said. "I was fortunate enough to play for London Irish in the first London double-header, and every year it has grown.
"Coming to the Millennium Stadium, with the roof closed and lots of spectators, it should be a great occasion we can all embrace and enjoy."
Edwards, meanwhile, confirmed Dan Lydiate will continue his comeback on Saturday from a serious ankle injury that sidelined him for almost six months.
Flanker Lydiate featured against the Ospreys last Friday and a run of late-season appearances could easily put the Wales star in contention for this summer's British and Irish Lions tour of Australia.