ENGLAND - TOM YOUNGS
Such has been the rise of Tom Youngs on the international scene that Dylan Hartley, seemingly England's captain in waiting 12 months ago, now is not even guaranteed a starting berth.
The Leicester hooker, who less than four years ago was converting himself from a centre, started all four autumn internationals for England in the No.2 jersey with Hartley injured.
Youngs first taste of the international scene came on last summer's tour to South Africa and while the 25-year-old only featured in the midweek games it was enough to get him noticed.
Whether he can continue his run of starts in this year's RBS 6 Nations remains to be seen but look for Youngs to feature prominently even as a replacement with his tireless work in the loose.
FRANCE - JEAN-MARCELLIN BUTTIN
Still only 21 but already with plenty of Heineken Cup experience under his belt, Jean Marcellin-Buttin has the opportunity to really cement himself on the international scene this year.
Buttin, who can cover wing or full-back, was named in Philippe Saint-Andre's experimental squad for last year's RBS 6 Nations and impressed in cameos off the bench.
A year older and with another season of top-flight rugby under his belt Buttin now has the chance to nail down a starting berth with Les Bleus.
His main rival for the No.15 jersey, Brice Dulin, looks to be struggling with an adductor muscle problem for France's first game and the mercurial Buttin will be hoping he can start his shift from potential to perennial France starter.
IRELAND - SIMON ZEBO
Ireland are not short of options in their back three but it is a sign of Simon Zebo's exponential improvement that the 22-year-old has jumped to the front of the queue for a starting berth.
The Munster flyer is in red-hot form at the moment, running in a hat-trick for the Irish region last weekend against Racing Metro to secure their passage through to the knockout stages of the Heineken Cup.
This autumn's dramatic arrival of Craig Gilroy on the international scene proves that Declan Kidney is not afraid to put his faith in youth and the 2013 RBS 6 Nations could be Zebo's time to shine.
ITALY - TOMMASO BENVENUTI
Only 22 years old but already a mainstay of the Italian backline, Tommaso Benvenuti has been on the lips of scouts around Europe for many years now.
The versatile Benvenuti burst onto the scene back in 2010, making his debut for the Azzurri after number of impressive performances for Treviso in the Heineken Cup.
He started every game last summer on the wing but has now firmly established himself at outside centre for club and country.
And the 23-cap man will hope to continue Italy's growth under Jacques Brunel in this year's tournament, starting with the visit of France.
SCOTLAND - STUART HOGG
Stuart Hogg's revelatory performances for Scotland in last year's RBS 6 Nations were the highlight of an otherwise forgettable wooden-spoon campaign.
The twinkle-toed full-back, who is a long distance relation of George Best, mesmerised defences and looked every inch a star of both the present and the future for Scotland.
Hogg's season this time around has struggled to live up to his meteoric rise as the Glasgow Warrior has been forced to split game time at full back with Peter Murchie.
And with Murchie also included in Scotland's squad Hogg will need to rediscover his best form in time for the 2013 tournament.
WALES - JONATHAN DAVIES
The 24-year-old Scarlets centre was one of the more underrated components of Wales' grand-slam winning 2012 RBS 6 Nations.
The powerful centre formed a magnificent pairing in midfield with Jamie Roberts and will be a key part of Wales' attempts to right the wrongs of the autumn internationals.
Both Davies and Roberts have struggled with injuries since last year's success under Warren Gatland but both look to be coming back to form and fitness at the right time.
And if the 31-cap man, who missed the majority of Wales' disappointing autumn series through injury but did return for their last-ditch defeat to Australia, can return to his destructive best few would bet against it.