Just as Shaun Edwards, Wales' brilliantly acute English defensive coordinator has identified Harinordoquy - and, not so far behind him, biting full-back Maxime Medard - as the Frenchman most committed to the idea of winning, France have piled so much of their World Cup bounty on stopping Roberts.
The French centre Aurelien Rougerie yesterday said that he considered Roberts the best, most compelling figure of his own trade.
He said Roberts carried the threat of perpetual aggression. "His team moves forward every time he touches the ball. He is the centrepiece of his team. People ask why these young Welsh players are making such impact here, why we have to consider the challenge they represent so carefully. We have to start with Roberts because in his case it is so simple," he said.
"Yes he has authority - it is that of a great player."
Harinordoquy has enjoyed that status for many years, of course. Last year he was the northern hemisphere's only candidate for world rugby's player of the year, and some were not so sure that justice was entirely served when the winning vote went to the All Black captain, Richie McCaw.
Yet for all the certainties of his nature, which made him a brilliantly combative sportsman in various disciplines before professional rugby, there have also been the squalls of temperament that have not always made him a coach's delight.
A great man, yes, an uncomplicated one, no. Except, that is, in the matter of his extreme antipathy for the idea of ever again being beaten by the English. "Why do you hate the English so much?" he was asked in his youth.
"Because they are English," he said with hardly a hint of a smile. More than anything, though, the dislike has been fuelled by two unbearable defeats, both in the semi-finals of the World Cup, in Sydney's Telstra stadium in 2003 and, worst of all, in the Stade de France, four years ago.
"It is true they were terrible defeats and, yes, of course they stick in my gullet. They make me want to be sick," he said the other day.
Yesterday his coach, Marc Lievremont, who played 25 times for France as a flanker and though born in Senegal prides himself on his knowledge of Basque instincts after playing inside and then along their borders in a nine-year stint with Perpignan, was looking much less like a man driven into a desperate corner. In fact, the apparent victim of a full-scale mutiny after the pool defeats by New Zealand and Tonga, was talking confidently of the new strength of his team's psyche after the defeat of the English.
Not the least source of the new serenity - after announcing an unchanged team - is the sense within the French camp that he scored a masterpiece of motivation when keeping Harinordoquy on the bench for the All Black and Tonga games.
"The coach was counting on Harinordoquy coming into the England game with a huge point to prove," said one French insider.
"Lievremont knows Basque pride and the anger that comes at any slight to it and the kind of motivation that provides. It was a great performance from Harinordoquy - maybe decisive in the way it set the tone. It may just have changed everything as far as this campaign is concerned."
Medard, the full-back who punched in the try that went so far in delivering England's death sentence at the weekend, talks of regained passion and confidence. "We had a bad time, yes, but I believe we are in the right mood to avoid any complacency after beating England," he said. "We have also beaten Wales in our last three games but we don't need telling that this young Welsh team has grown very strong.
"They will not be easy but you know we have a very strong desire now. It is to show a new facet of French rugby - our ability to be more consistent."
Yet if Lievremont has the demeanour of a man just released from the Bastille there is also still a certain caution. "It is necessary to remember that victory can, like defeat, sometimes tell you everything and nothing. The point is that the England match is over - we have different opponents offering new dangers." Independent
