There is a long and noble tradition of brothers putting on their kit and playing rugby together for Scotland.

There is also a shorter, and arguably less noble, tradition of Scottish brothers whipping said kit off and parading themselves in the pages of the Dieux du Stade, the racey and boldly homo-erotic calendar which is produced each year by Paris side Stade Francais.

Sean and Rory Lamont stripped off in the 2007 edition, while Max and Thom Evans did likewise in the 2010 version. Yet for all that those efforts were generally well received, and mostly pretty tasteful, the only things Jonny and Richie Gray want lay bare are their talents as rugby players.

Between them, the Gray brothers pack close to 40st of muscle and menace, but they both looked pretty coy and sheepish yesterday when they were asked if they would ever consider going au naturel for the celebrated calendar. Eventually, Richie offered a terse and embarrassed "no", looking down at his chest as he spoke. At least, we think it was his chest he was looking down at.

If anything, Jonny looked even more appalled by the suggestion. Yet on the subject of appearing alongside his elder brother - Richie is 25, Jonny just 20 - for what will, bizarrely, be the very first time, the younger Gray was rather more animated. "It was a very special moment for both of us," said Jonny of learning of their joint selection to play Argentina on Saturday. "Really surreal."

Strictly speaking, they have been on the same pitch at the same time for Scotland, but it was only for a few seconds in the Murrayfield match with South Africa last year, as Jonny trotted on after 62 minutes to win his first cap and Richie trotted off to make way for him. Neither did they make a joint appearance for Glasgow, for Richie was already on his way to Sale - and, subsequently, to current club Castres - before Jonny made his breakthrough at the Warriors.

It is not quite so true to say they have never played against each other, but that box is only ticked if you include their clashes in the back garden of their childhood home near Glasgow. Both recall those battles as pretty abrasive affairs but they were also pretty one-sided. "When you are a 12 years old and your brother is seven, it is a bit easier," explained Richie. "As he got older he got a bit harder."

The dynamic between the pair is fascinating. Now, as then, there is a curious mix of fondness and sibling rivalry.

"To be involved in the Scotland set-up is special anyway and we are very grateful to be here," said Jonny. "But it will also be very special and emotional to be representing Scotland beside my brother."

For all that Richie is older and more experienced, it was Jonny who was first to turn to rugby, being taken along to Cambuslang minis by a neighbour. It was only when he saw how much his kid brother was enjoying the sport that Richie, who now has 39 caps to Jonny's five, decided to give it a go. Even now there is a sense that Jonny, who will take charge of the lineouts against the Pumas, is still the brains of the operation.

"Jonny is the boss," said Richie with a smile. "He tells me where to go. I just shut up and listen. In saying that, corny as it sounds, we like to bounce ideas off each other. If he thinks he can do things better he will tell me. Likewise if I think I can do it better I will tell him. That's the way it works."

Yet Jonny pays credit where it is due as well. "I have seen Rich growing up working really hard to get where he is on and off the pitch," he explained. "I saw his work ethic, the extras he has had to do at home, his diet, his extra fitness, his extra weights. It was something I knew I had to do. Watching him was useful."

The younger Gray also remembers how friends used to tell him that he would one day be playing in the same Scotland team as Richie and how he dismissed their predictions. "I never thought it would be true," he said. "I used to laugh it off. It will be very special on Saturday, but on the pitch it will still be pretty hard."

Vern Cotter, the Scotland coach, praised the two locks for the power they bring around the fringes of the rucks. Richie has added layers to his game in that regard since his move out of Scotland, while Jonny has always had a huge workrate at close quarters. As noteworthy as their family connection might be - they are the 47th set of brothers to play for Scotland - how they combine as players will also be fascinating to see.

Indeed, Jonny stressed that their celebrations after their joint selection were brief, for the news had no sooner sunk in for both of them than they were back out on the training pitch again. "We knew we had to get our heads down and focus on that," he explained.

Richie's most recent appearances for Scotland were in the summer tour wins against the United States and Canada. Jonny then carried the family flag to Argentina, helping the national team to extend Cotter's unbeaten run to three games before that streak was ended by the hefty 55-6 defeat by South Africa just a week later.

Yet while recent form offers mixed messages, Richie is confident that the side is developing a style that can be effective as a raft of new faces emerge. "Everything feels pretty sharp," he said. "It feels fluid. We are creating gaps and space. It is credit to these young guys coming through and the other guys in the squad. They have performed exceptionally well and trained exceptionally well.

"So I'm really looking forward to seeing how we go at the weekend. In saying that we are going up against a great team that is coming off the back of a great win in the Rugby Championship [Argentina beat Australia last month] so it will be a tough match."