If Martyn Williams is the oil in the Welsh engine, David Wallace is the horsepower to Ireland's.
These are two different types of players operating in the same position, two outstanding candidates that went man-against-man to be first choice openside on the British & Irish Lions tour to South Africa last summer.
Nine months later, nothing much has changed for two old soldiers -- Wallace, 33, and Williams, 34 -- approaching the end of their careers. The fire still burns inside of them and they want the heat of competition to last up to the World Cup in New Zealand next year.
The Welshman has been given the honour of leading out Wales at Croke Park because regular captain Ryan Jones has not been able to beat the enemy that is injury.
Williams is no stranger to leadership, captaining his beloved Cardiff for three years (2002-2005). He first led Wales against Scotland at Murrayfield in 2003.
He will become Wales' most capped forward tomorrow, taking him past a tie with Colin Charvis, on the occasion of his seventh time in charge of his country.
"I was honoured and excited when Gats asked me," he said. "It is something I've done a few times before, so I am really looking forward to it. I am happy to step into the role for Wales."
It is one hell of a turnaround. Williams announced his retirement from international rugby at the end of Wales' exit from the 2007 World Cup. This didn't last long.
He was soon convinced by coach Warren Gatland to return in January 2008.
However, the recent inadequate form of Wales has led to calls, in some quarters, for Williams to be sent into final international retirement.
"When I came out of retirement a couple of years ago, I was warned by a very experienced player, 'as soon as you have a bad game when you are over 30, people will automatically call for you to be dropped and say there needs to be a change'," he said.
"So I knew it was only a matter of time before it was going to happen to me. It is water off a duck's back, really. People say they want change and that's fair enough. It is just one of those things.
"As a player, you cannot let that influence you in any way or wear you down. You've just got to concentrate on going out and doing the best you can.
"I don't think my form has been that bad, to be honest with you. Obviously, a lot of people do, but provided my team-mates and the coaches are happy, that is the main thing," he said.
It leaves the veteran Williams with a lot to prove at a time in his career when that should be the last thing on his mind. Certainly, Wallace knows his qualities.
"He is a very good footballer and he does a very good job as a seven in terms of poaching balls if you leave yourself open for him to come in and pilfer," said Wallace.
"He can also play like an out-half or a winger at times as well. He can put little kicks through and he has soft hands. There's a wide range of skills.
"I've played against him a number of times going back to Under-21s and I've had two (Lions) tours with him so I've seen what he brings. He's a good leader and guys want to play for him.
"I suppose it's up to us to discourage him. It's hard to pick fault in his game to be honest, though I think his work in poaching probably is his biggest strength."
The Irish flanker has enough on his plate without worrying how his old adversary is going across the Irish sea. Leinster's Sean O'Brien and Shane Jennings are making headway. Ulster's David Pollock is finally finding his feet away from injury.
The Munsterman has long been judged one of the untouchables on the Irish side, his pace and power, from those piston-like legs, responsible for so much of Ireland's go-forward.
He prefers to discuss Ireland the team rather than Wallace the individual. It has always been his way to be available for the press without ever giving them too much to chew on. He is the ultimate professional.
"It wasn't the end of the world against France," he said. "Likewise, but for that last try (in Twickenham), we would have been looking at a defeat and it could have been total doom and gloom.
"So it's about trying to keep a level head after these games," he added, in a manner more than similar to that of his head coach.
It is typical of a player, like Williams, who knows the value of doing his talking on the pitch.
It is the only place it really matters.