It is certainly not a sign of flamboyance, like those twirled by the Comte d'Artagnan and his pals. The moustache of Marc Lièvremont, grown since his arrival in New Zealand, is an altogether more puzzling manifestation, as resistant to interpretation as its owner.

Before its appearance, France's 42-year-old head coach cut a passably debonair figure. With it, he looks like a character from a film by Claude Chabrol: the head of the gendarmerie in a small town in the Périgord, say, nursing tender feelings for the local schoolmistress, a lovely young widow, his nose put badly out of joint when a senior figure arrives from the Sûreté Nationale in Paris to apply a more sophisticated expertise to the unmasking of a local serial killer while effortlessly winning the teacher's heart.

Behind Lièvremont's unconvincing smile this week lurks the disappointment of having his authority publicly undermined. He tried hard to maintain his dignity at the start of a remarkable sequence of press conferences, but seemed chastened as he more or less apologised for describing his players as "spoilt brats" earlier in the week. Later on the players themselves trooped in, looking in varying proportions uneasy or truculent, to confirm how much they had resented his criticisms. It was hard to believe that any of them, coach or players, were so close to what could be the greatest occasion of their rugby lives.

Those who claim to detect a plan behind the apparent breakdown in the relationship between Lièvremont and his players, aimed at throwing the favourites off balance, are surely in danger of disappearing up their own conspiracy theory. The truth seems to be that the players, dissatisfied with the general quality of their training and with the head coach's habit of insulting them in public, now seem to be attempting to draw themselves closer together, creating their own siege mentality in preparation for the attempt to stop the All Blacks repeating the result of the inaugural World Cup, when the home team trounced Jacques Fouroux's France 29-9 at Eden Park.

It is a sad situation for an authentic rugby man. Born in Senegal to a father serving in the French army, Lièvremont grew up in Argelès-sur-Mer, in the eastern Pyrenees, alongside five younger brothers and a sister, all of whom played the game at a high level – including the sister, Claire, a champion of France with the local Toulouges club. Marc played as a flanker for Perpignan, Stade Français and Biarritz while amassing 25 international caps and a place in the team that lost to Australia in the 1999 Rugby World Cup final after so thrillingly eliminating the All Blacks a week earlier. None of that, however, seems to count for very much at the moment.

"Win or lose, he will be a lonely man when all this is over," someone close to the France camp said this week, and the Auckland daily paper carried a photograph of him on Friday sitting on the window ledge of his hotel room, smoking a cigarette and looking like a man without a friend in the world. The general feeling is that he has done so much damage to his own reputation that not even an historic victory on Sunday would be sufficient to restore it.

Win, and it will be the players – notably such assertive characters as William Servat, Lionel Nallet, Imanol Harinordoquy and Vincent Clerc, all of whom won their first caps before Lièvremont's arrival in 2007 – who receive the credit for pulling the team out of the slough of despond created by the head coach's scattergun decision-making and a motivational approach widely seen as self-defeatingly provocative. Lose, and it will be down to him for squandering the good fortune that took the team past Wales in the semi-final and prompted Eric Blanc, the former France squad member and current co-president of Racing Club de Paris, to remark that Lièvremont "must have been sharing his hotel room with God" last week.

When he was given the job in 2007, a few weeks before his 39th birthday, it was amid sighs of relief at the departure of Bernard Laporte, "Mad Bernie", an intense, fast-talking former scrum-half whose eyes glinted behind his rimless spectacles as he firmly denied the existence of any such thing as "French flair". Appointed by Bernard Lapasset, the president of the French federation, Lièvremont had begun coaching only five years earlier, after a persistent knee injury ended his playing career.

His experience as a coach amounted to two seasons with the Biarritz youth team and two more as head coach of Dax in the second division, during which time he also spent three years in part-time charge of France's under-21s. His connections within the federation were said to explain why he got the nod ahead of such experienced and better qualified figures as Guy Novès of Toulouse, Patrice Lagisquet of Biarritz and Philippe Saint-André, then with Sale Sharks (and the man who will take over when Lièvremont stands down after this tournament).

At the start the new head coach claimed that his priority would be to free the team from the shackles of Laporte's pragmatism. Drawing freely from the pool of young talent in the under-21s, he chose more than 50 players during his first Six Nations season. Some of the selections puzzled observers: where now are Julien Malzieu, Lionel Faure, Arnaud Méla and Loïc Jacquet from that initial squad?

Of Sunday's squad, only Morgan Parra, Maxime Mermoz, Alexis Palisson and Maxime Médard can be seen as Lièvremont's protégés, while three others – François Trinh-Duc, Fulgence Ouedraogo and Fabien Barcella – are on the bench. As he has fallen back on the experience of those who played under Laporte, so his tactical horizons have shrunk. Despite some fine tries in this tournament from Clerc and Médard, a collective commitment to le beau jeu has been conspicuously absent, particularly when failing to take advantage of a Wales team reduced to 14 men for an hour of the semi-final.

"He is not the best communicator in the world but he is a very good coach," his team manager, Jo Maso, claimed this week. A winner of 25 caps between 1966 and 1973, Maso has managed five grand slam teams under four coaching set-ups since 1997 and will be going to his second final in Sunday. "In 1999 I remember there was criticism for no attacking play, yet after we won the semi-final everyone said they were great coaches," he said. "In two or three years' time, people will remember only that Marc Lièvremont took France to the final of the World Cup."

No one, however, is calling Lièvremont a great coach. He has enjoyed his good moments over the past four years, notably a victory over the All Blacks in Dunedin in 2009 and another in Toulouse a few months later against the Springboks, the reigning world champions, followed by the grand slam of 2010. Since then, however, the embarrassments have piled up: a 59-16 spanking by the Wallabies in Paris last November, a 22-21 reverse in Rome this year, and defeat by Tonga in Wellington three weeks ago.

"Motivation is a collective thing in this French team, not an individual business," Maso said, trying to spread the burden, and the players joined the chorus. "We are going through this as a team of 30 with a common objective," Damien Traille said on Friday. "We're not alone because we prepare together," Servat added. "Reading that stuff about 'us against the world' is a great way to prepare for a match of this magnitude," Nicolas Mas observed. "It means we don't need much motivation. Maybe afterwards we'll thank you for it."

But if a head coach is not an effective motivator, what use is he? Tune in on Sunday for the answer.