As Ireland go in search of an unprecedented third straight title, Irish coach Joe Schmidt has turned to Munster captain CJ Stander for the No.6 jersey, and it will be his maiden international run-out.
And if Stander needs reassuring then all he has to do is look around him at his fellow men in green, with fellow Munster teammates Simon Zebo, Keith Earls, Conor Murray and Tommy O'Donnell all starting against Wales.
Leinster, great rivals of Munster in the GUINNESS PRO12, also have five players in Ireland's starting XV in the form of Jonathan Sexton, Jack McGrath, Mike McCarthy, Devin Toner and No.8 Jamie Heaslip.
Ulster hooker Rory Best will captain Ireland for the first time, with teammates Jared Payne and Andrew Trimble at centre and right wing respectively, while Connacht duo Robbie Henshaw and RBS 6 Nations debutant Nathan White completing the line-up.
WALES
The stars in green will come up against familiar faces at the Aviva Stadium on Sunday with Warren Gatland's Wales side featuring 11 starters from the GUINNESS PRO12.
And there will be no one happier in a red shirt on Sunday than Tom James, whose return to Cardiff Blues has seen him handed the No.11 jersey for the clash with Ireland as he makes his first start for Wales in six years.
Fellow Cardiff Blues star Gareth Anscombe will look to build on his impressive Rugby World Cup outing as he starts at full-back, while teammate Sam Warburton once again leads the side from the back row.
Ospreys are the most represented Welsh GUINNESS PRO12 side with four of the starting XV in the shape of Dan Biggar, Scott Baldwin, Alun Wyn Jones and Justin Tipuric.
Scarlets youngsters Gareth Davies, Rob Evans and Samson Lee are all handed starts, while Taulupe Faletau is flying the flag for Newport Gwent Dragons.
SCOTLAND
Scotland has also turned to 11 GUINNESS PRO12 stars as they look to build on a promising World Cup campaign in their RBS 6 Nations opener against Auld Enemy England.
Scarlets John Barclay is the odd-one-out with the remaining ten starters being split evenly between defending GUINNESS PRO12 champions Glasgow Warriors and their local rivalsEdinburgh.
From the Warriors, Scotland head coach Vern Cotter has turned to Stuart Hogg, Mark Bennett, Tommy Seymour, Finn Russell and Jonny Gray.While Matt Scott, Alasdair Dickinson, Ross Ford, Willem Nel and John Hardie complete the Edinburgh contingent.
ITALY
The GUINNESS PRO12's two Italian sides are also evenly represented with five players apiece in Italy's starting XV for their clash with France.
Leonardo Sarto, Gonzalo Garcia, Carlo Canna, new boy Andrea Lovotti and George Biagi will swap Zebre shirts for Italian ones this weekend, while Benetton Treviso are represented by Edoardo Gori, international debutant Ornel Gaga, Marco Fuser, Francesco Minto and Alessandro Zanni.
And with a further 26 GUINNESS PRO12 stars raring to come off the bench after being announced among the various replacements, fans of all 12 GUINNESS PRO12 clubs will be watching on with plenty of interest this weekend.
After each game in the RBS 6 Nations championship, as long as a GUINNESS PRO12 player has scored a try, one fan will be selected at random from all of our Twitter competition entries using the hashtag #GUINNESSPRO12Hero and they will win a pair of tickets to the GUINNESS PRO12 Final (May 28, BT Murrayfield). PLUS, if that's not enough, all of the winners of the competition will be entered into a ballot for the chance to have their tickets upgraded to hospitality and win a ball signed by the winning team in the GUINNESS PRO12 Final.