The British & Irish Lions tour to Australia hangs like a golden carrot in front of the Welsh and Irish players when they walk out at the Millennium Stadium this afternoon.
"It is as far as you can go. It is the pinnacle of your rugby-playing career," said two-tour British & Irish Lion Fergus Slattery, the fierce Ireland openside of the 1970s.
"As a rugby player, you want to get onto your national side whether it's England, Scotland, Wales or Ireland. Having established yourself, you want to play for the Lions."
Former Wales wing Ieuan Evans set the stage for what is certain to be an intriguing Six Nations, with everything on the line in terms of the tournament itself and the benefits that can accrue for Australia.
"When you look at a Lions year, you look at your autumn internationals as your mock exams and the Heineken Cup as your coursework. The final exams are all about the Six Nations," said Evans.
"There are a number of potential head-to-heads, with Warren Gatland watching all these games to see who will make their way onto that plane.
"There is so much at stake as well as the chance of winning a Six Nations championship or a Grand Slam," he added.
The individual head-to-heads between Ireland and Wales are enough to make the mouth water as Declan Kidney schemes to win there for the first time since that Grand Slam day in 2009.
ROB KEARNEY v LEIGH HALFPENNY
Ireland's Kearney has been hampered by a lower back injury that put him out of Ireland's November series and most of Leinster's Heineken Cup campaign.
The Leinster man is head and shoulders above everyone in Europe in the air, a physical presence as last man back and an effective attacker who has always been a big-game player.
The Cardiff Blues' Halfpenny is a siege-gun long-range kicker with a steely nerve, something that has endeared him to coach Gatland.
He does, however, lack the physical presence as a smaller man than Kearney, though no one can doubt his bravery to confront the giants that roam international rugby waters.
SIMON ZEBO v GEORGE NORTH
Munster's Zebo has always been a one-off, unique talent. He is blessed with natural size (6'2" and 15st) and real speed as the quickest player in Irish rugby.
There was a time when his work ethic was in question. That issue has been resolved. He has shown distinct improvement in the air and in his attention to defensive detail.
There is a lingering suspicion that Wales have not been able to take advantage of the special gifts with which North has been endowed.
In fact, he started out as an outside centre and his skills set are better suited to a role where he can have more of a direct influence. He has the talent to become to the Lions what Ireland's Tony O'Reilly was at one time.
BRIAN O'DRISCOLL v JONATHAN DAVIES
This is the most interesting and, potentially, the most influential one-on-one of the lot as O'Driscoll works to turn back the clock against a powerful, young foe.
The old warrior, just turned 34, has an iron constitution for contact and has mastered the defensive aspects of the position while retaining his impact on attack, more through putting others into space rather than taking it himself.
The Scarlet Davies is not the one-dimensional straight-line runner who first burst onto the international scene as a 21-year-old in the summer of 2009.
There could be an issue, like there could be for Manu Tuilagi, over the lack of creativity he brings to the game as an average passer with limited imagination.
CIAN HEALY v GETHIN JENKINS
Leinster's Healy has been tearing up pitches all around Europe this season in the Heineken Cup. Where others failed to fire, he was on fire.
The explosive, athletic nature of his game and the appetite for work are a sight to behold. There remains some doubt over his ability to scrummage against the very best tight-heads in the world. Cue Adam Jones.
Out of sight is never out of mind with Jenkins, an all-round operator just as at home in the tight as he is the looser elements of the game.
The question is whether his powers of persuasion have diminished at this level given the number of miles on the clock for the 94-times capped 32-year-old Wales prop.
SEAN O'BRIEN v Sam WARBURTON
The Tullow Tank brings a different dimension to the openside than Warburton as a modern-day body blasting carrier who almost guarantees the gain line. The successful Welsh plan to take him low at the 2011 World Cup has forced a rethink for a versatile back rower who can operate in all three positions.
The Welsh captain was talked about as the most likely Lions leader in the aftermath of the World Cup, where he was a dominant force at the breakdown.
Since then, he has let his standards slip to such a degree that he is lucky to hold off the consistent and conspicuous claims of Justin Tipuric. He will be under the microscope.
JAMIE HEASLIP v TOBY FALETAU
Ireland's new captain has tailored his game as the years have rolled by, narrowing his focus to become the complete package as a worker and collaborator of play. His control at the base of the scrum is consummate, his link play sure-handed and he is the owner of an engine that never stops running.
Like Warburton, Faletau burst on to the scene at the 2011 World Cup as a 20-year-old novice and a ferocious ball carrier, taking the ball on at pace.
The problem has been second season syndrome. He quickly became a marked man and has struggled to cope with the extra attention paid to him by defences.