"Stand there, you fat pig! This is where I told you to stand. Do it how I told you!"

Johnnie Beattie would wince as Fabien Galthie prowled the Montpellier training pitch, hauling players about by the earlobes, spitting venom at those who did not follow his orders to the letter, reducing monstrous specimens to rubble.

The little coach could eviscerate his troops. The verbal torching he visited upon many forced them out of the club. Beattie's tales - some unrepeatable - conjure visions of a tyrant in a tracksuit, yet the former Scotland number eight regards Galthie as the finest tactical mind he has come across in nearly two decades as a professional.

In his first season at the helm, Galthie is two games from piloting France - beleaguered, meek and mutinous for an age - to a Six Nations Grand Slam, a feat they have not managed since 2010. Scotland, on Sunday, and Ireland, six days later, stand in their path.

'People had their confidence destroyed'

In 2012, the pugnacious former French captain and scrum-half took Beattie from Glasgow Warriors to France, where he spent the next eight years of his career before retiring in January.

"He's the best technical coach I worked with," the Scot says. "He was absolutely fantastic, ahead of the curve, but he struggled with player management. He struggled with being a decent human you want to buy into and work for. People bought into the fantastic rugby we played, not the culture or environment he would provide.

"Even back then, I was with guys like [All Black] Rene Ranger, [France fly-half] Francois Trinh-Duc and [former Georgia captain] Mamuka Gorgodze and we all said this guy would be absolutely amazing in an international environment, where he's not with players week in, week out. And it's pretty evident that he is leading that resurgence with the French national team."

Beattie describes playing for Galthie as "survival of the fittest", a ruthless habitat where plenty cracked when the abuse and the savaging grew too much to bear.

"Our prop, Yvan Watremez, came in one morning with stomach pains from fear," he says.

"I remember [assistant coach] Mario Ledesma screaming at a tight-head prop in a scrummaging session to try and work his way through the scrum to get the cheeseburger at the other side of it because he's a fat pig. I laugh now, but when you're in the environment, it was complete humiliation.

"Some people crumbled and didn't stay very long - a few capped internationals came and went within two or three months. A lot of people had their confidence destroyed, needed to get out, or were bullied.

"He was a real Jekyll and Hyde of coaching in that he was absolutely wonderful in technical stuff but also very capable of burning personal relationships and burning a club environment. I struggled to stomach how he was with other people."

'He has re-instilled their pride'

Despite the vitriol, these are years Beattie looks back on with fondness. Galthie respected him, allowed him to flourish on the field, and gave him a route to a new life in France.

Whatever his methods with the Test team, they are, emphatically, working. In Shaun Edwards, Galthie has the defence coach he has long admired and coveted, the snarling lieutenant to Warren Gatland at Wasps, Wales and the British and Irish Lions. He has a crop of phenomenally talented young players with Junior World Championship medals, unencumbered by the malcontent of the past.

France bludgeoned England with their blitz defence, motored past a weak Italy side and put Wales to the sword in Cardiff for the first time in a decade. They stand on the verge of greatness, a rampant championship few foresaw.

"A lot of Fabien's blitz defence system was based on Edwards. Shaun will add the professional grit that we haven't seen to a French side for a few years," Beattie says. "French rugby has been in the doldrums. They've lost a lot of their self-respect as a public and as players. Fabien has re-instilled that pride really well.

"That's been the great bit about the renaissance, they believe in themselves a bit more. People want to see a French team flying, they want to see flair, aggressive defence, a big scrum - it's great for the tournament."

'Beat their blitz and there's a chance'

Scotland, so far, have the best defence in the tournament, but that new-found steel will be sorely strained on Sunday. Without the ball, they have been too wasteful, scoring only three tries to France's 11. How do they put a stop to this reinvigorated juggernaut?

"I would really target their tight-head props," Beattie suggests. "Both Mohamed Haouas and Demba Bamba are big athletes but really average scrummagers.

"To beat their blitz defence, Scotland have to kick to contest - shorter cross-field kicks into no-man's land that force the covering players to come forward and create aerial 50-50s. Get them retreating and then their blitz is ineffective. If Scotland can get in the middle of the field to restrict that blitz, kick properly and destroy that tight-head side of the scrum, there's a big chance."

To thwart Galthie, Scotland will need their go-to men firing and their attack to click in a way it hasn't this championship. It is a mighty task, but pull it off and there will no doubt be few eardrums reverberating in the French dressing-room.