The crescendo of this Tour de France may peak on the long climb to Andorra on Friday when the peloton’s two heavyweight prizefighters finally get the chance to slug it out. It is only the first round, yet Alberto Contador has it in him to land a killer blow on Lance Armstrong and there is a sense here of months of speculation reaching a climax.

It may have seemed reasonable, then, for Thursday to have been something of a breather before the bout begins. However, the all-Spanish stage from Girona to Barcelona brought with it rain, tour-ending crashes and the thrilling sight of a Briton — and not Mark Cavendish — tearing hell for leather in search of a stage win.

It would have been more thrilling, as is always the case with David Millar, had he never been tempted by performance-enhancing drugs. Yet he now ardently flies the anti-doping flag and on Thursday he was leading a courageous one-man charge through the streets of Barcelona and into the climb up Montjuic hill to the finish in front of the Olympic Stadium.

Indeed, at one stage on Thursday, when he was ten kilometres out, this was a thoroughly British day. Cavendish had, and still has, the green jersey and Millar had stretched his break so far that he was the “virtual leader” of the Tour.

But as Montjuic loomed closer, so did Millar’s pursuers. The wide city boulevards allowed the peloton to work together and take large chunks out of the lead and when Millar turned to look, with barely a kilometre to go, he saw them snapping ravenously at his back wheel and his spirit was broken.

That moment feels “like someone’s unplugged your power”, he said. “You go from being fired with adrenalin to the power going and you die.” And in his case, that meant slipping back to 96th place.

Up ahead, there unfolded a finish of real significance. The gradient up Montjuic was always likely to discount Cavendish and, in his absence, the winner’s podium was filled instead by a sprint rival, Thor Hushovd, the Norwegian riding for the Cervélo team.

So while this race already had the mouthwatering rivalry between Armstrong and Contador, on Thursday heralded another genuine fight — the one for the green jersey, battled for by the sprinters. Cavendish has worn it since Sunday but after yesterday, his 26-point lead has been cut to one.

The peloton now has so much respect for Cavendish that it has been denying him and his team any help in the hope that he will blow himself out. Cavendish insists that he is not motivated by the green jersey and simply wants to get to Paris for the first time. Yet if he does, it looks likely that he or Hushovd will be in green.

The next three days, however, launch the riders into the Pyrenees, where Cavendish and Hushovd will go into survival mode, while Armstrong and Contador, Astana team-mates and race rivals, go head to head, starting with today’s 224-kilometre stage.

“I know Alberto wants to assert himself in the race,” Armstrong said. “I don’t need a team meeting to know that. I know he’s ready to go. If he goes and nobody can hang with him, then I’ll just be with the other leaders, that’s the way it will be.”

The way Armstrong makes it sound, it would not hugely bother him, but he rarely drops a comment that does not somehow toy with Contador’s mind. Barely anyone here believes that Armstrong is the stronger of the two, although the fear for Contador is that he may be so keen to make a statement today that he goes out too strongly and beats himself.

Bradley Wiggins, who has a box seat in the peloton here, believes Contador should hold back. “He’s going to win the Tour whatever, so if he wins the tour tomorrow, or on the Ventoux [yellow], it doesn’t matter,” he said. “He puts more pressure on himself if he takes the [yellow] jersey. I’m saying that as a fan of Contador. Logic tells me he should keep it cool tomorrow.”

That may be logic, but neither he nor anyone believes Contador will follow it.