When Wales start the defence of their Six Nations title against Ireland in Cardiff on Saturday there will be no individual tussle with more focus trained on it than that between Sam Warburton and Jamie Heaslip.
Warburton, the Wales captain, and Heaslip, who leads the visiting side, both pack down in the back-row and will bid to mentally and physically outmuscle each other in the 80-minute battle of supremacy.
Their private set-to in the dark recesses of the breakdown is just the beginning of a series of rivalries with opposing captains throughout the five-round tournament because, aside from Pascal Pape of France, each country is led this season by a back-row forward.
After the Welsh showdown with Ireland at the Millennium Stadium, England's captain Chris Robshaw will eyeball Scotland's Kelly Brown at Twickenham while Italy's No 8 Sergio Parisse will scrum down in the opposite pack to Pape, a lock, when France travel to Rome on Sunday.
It follows the template set out by New Zealand and Australia, who in Richie McCaw and David Pocock respectively have two of the world's best open-side forwards that mix their day job of creating havoc in opposing teams with the extra-curricular activity of managing others.
There is a certain irony that where a captain needs to be inclusive and provide a link between the players and the coaching staff a flanker is a marauding menace who frequently acts alone.
McCaw has blended the two roles to perfection during his 71-match tenure for the All Blacks and Warburton believes that it makes sense to appoint back-row forwards in the leadership role.
"You are in close contact with your front five and your back line," the Cardiff Blues No 7 said. "Back rows have to know all of the plays as well as the kicking game as you need to know your running lines. As far as the team make-up goes and the game plan you probably know the most as well as the No 10."
Heaslip has played many times against Warburton and Brown in the RabotDirect Pro 12 league that includes teams from Ireland, Wales and Italy.
The strapping 29 year old was only appointed in November because of injuries to Brian O'Driscoll, Paul O'Connell and Rory Best, all former captains.
To highlight the changing nature of the captaincy, whereby players are now part of a growing leadership group, Heaslip has leaned heavily on O'Driscoll, as well as Leo Cullen, who captains the pair at Leinster, the Dublin club side.
"When I was asked to be captain Brian was one of the first guys that I rang. I asked him some questions and he gave me some pointers," Heaslip said.
"In training he came straight up to me, shook me by the hand and told me he was 100 per cent behind me. I also got a text off Paul and Rory and I see Leo at training. It is quite humbling to learn off such players and lead them as they are your peers.
"Leo is very similar to me in that he is focused on the task in hand whereas Paul, and to a certain extent Brian, you see their passion coming out in their actions. I'm still wet behind the ears with regards to the captaincy and hopefully I can gain experience off them."
Heaslip is a smooth talker and by his own admission can go on for too long.
It is a sharp contrast to Brown, who was appointed the Scotland captain by the interim coach Scott Johnson precisely because he barely says anything at all.
Brown has got to grips with a lifelong stammer and the Saracens forward is cut from a similar cloth to O'Connell and O'Driscoll in that he leads by example.
"My view on captaincy may not be everybody's cup of tea, but I like doers," Johnson said. "I don't like the big talkers.
"The best captains I have worked with in the past have got their hands dirty, who get down and do it and show the way. I have a reluctance to have line-out or move callers as captain because you hear their voice so often."
Brown has the unfortunate task of leading Scotland out on to the Twickenham turf where his team have not recorded a win since 1983.
Back then, Brown was only seven months old, and Robshaw was not even alive, when a tide of passion drove Scotland to their 22-12 win in London.
There is a similar tide gathering behind Scotland's challenge this time after legendary Scottish coach Jim Telfer labelled the English as "arrogant" last week.
It caused a huge furore but with Scotland having scored only one victory away from home in the tournament since 2006 Brown understands that passion will only get his team so far.
"If you come down here all fire and brimstone you will get [beaten]," Brown said. "It is about finding that right balance. We need to play with passion, but it is about making sure that the fire blends with the cool up top."
Six Nations fixtures
Saturday Wales v Ireland: 5pm, England v Scotland: 8pm
Sunday Italy v France: 7pm
Feb 9 Scotland v Italy: 6.30pm, France v Wales: 9pm
Feb 10 Ireland v England: 7pm
Feb 23 Italy v Wales: 6.30pm, England v France: 9pm
Feb 24 Scotland v Ireland: 6pm
March 9 Scotland v Wales: 6.30pm, Ireland v France: 9pm
March 10 England v Italy: 7pm
March 16 Italy v Ireland: 6.30pm, Wales v England: 9pm, France v Scotland: midnight
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