‘Don’t Mess With Texas,’ the bumper sticker says and whatever the denouement of this year’s Tour de France, it will be a brave rider who takes on sporting legend, cancer icon and alpha male, Lance Armstrong, in pursuit of final victory. If Alberto Contador, the American’s Astana team-mate, chooses to be that man then it could be a career-defining moment for the young Spaniard.

Armstrong’s success over the past decade has brought new wealth into a professional milieu, which, for many years, could only cast an envious eye at the budgets in tennis, golf and football. The Texan is the sport’s biggest-ever star and many within cycling - including the Tour organisation, which relies heavily on income from lucrative contracts for television rights - have ridden the Armstrong gravy train.

Then there is the American’s enviable and influential contact book, which brings together spin doctors and Hollywood A-listers, fellow sporting icons and former American Presidents Clinton and Bush. Not to mention all of European cycling’s most influential figures.

Even when he retires (again), Armstrong is likely to remain a powerful figure. He is developing plans to launch his own Livestrong professional team and rumours persist of secretive attempts to put together a consortium capable of buying the Tour itself.

Contador’s mutinous mood, glimpsed briefly in Andorra, has won sympathy in some corners. “At the start in Monaco, they designated Contador as team leader, but then didn’t protect him,” Bernard Hinault, five-time Tour champion, said of the Astana team. “Then he rebelled [at Andorra]. That’s logical, but from now on between them, it’s war.”

During the Tour’s rest day, however, Contador was keen to play down talk of conflict. "If Lance attacks, I will not follow him,” he said. “There are other riders who have to chase him down.”

“My relationship with Armstrong is normal, just like I would have with any other rider,” he said. “We eat at the same table in the evenings, and it's an equally normal situation on the team bus. Maybe the tension seems greater from outside than it really is."

Yet, according to Armstrong, “there is tension”. Once the Tour enters the Alps, tension, or perhaps mind games, may turn to bitterness, if the two team-mates do ultimately turn on each other. Yet with only two summit finishes and one short individual time trial remaining, it may not be Contador who deals the decisive blow, but the Tour route itself, because Armstrong could simply run out of opportunities to gain the upper hand.

In his heyday, Armstrong made the most of mountain summit finishes and individual time trials. His seven-year reign as Tour champion was littered with prologue and time trial wins, summit finish victories, or ferocious attacks in the mountains that hammered home his domination.

In that light, last Friday’s summit finish in Andorra was ideal terrain for him to strike the first blow. Yet it was Contador who attacked and took the initiative.

Even so, Armstrong’s track record is daunting. Between 1999 and 2005, he asserted his authority by winning nine time trials and no less than 11 mountain stages. Intriguingly, of those 20 stage victories during his seven-year reign, ten came in the Tour’s final week and six came in the Alps.

Despite that, based on the results so far this year, in Monaco’s opening time trial and Andorra’s summit finish, he will be unable to contain Contador. On the other hand, the Armstrong of old usually got stronger as the Tour went on, which hints that he may be at his best as the race reaches its climax in the Alps.

Whatever the outcome, there is little doubt that Armstrong and Contador’s relationship could be irreparably damaged by the end of this Tour. In 1986, Bernard Hinault and Greg LeMond, co-leaders of the La Vie Claire team, fought out a bitter duel for the yellow jersey. LeMond accused the Frenchman of sabotage, while Hinault mocked the American’s paranoia. They are still not speaking to each other.