The Union Jack appears alongside the Barloworld team’s name on the Tour de France start list, but yesterday’s Alpine stage win in Briançon’s old town, by Juan Mauricio Soler, of Barloworld, was fashioned in the mountains of Colombia rather than in London’s West End, where the team’s head offices are registered.

Soler’s spectacular lone attack on the gruelling ascent of the Col du Galibier took him over the summit ahead of the chasing peloton and propelled him into the breakneck descent towards Briançon. Despite wrestling a gusting headwind, the 24-year-old Tour newcomer from Boyacá held off his pursuers to secure the best victory of his career.

In Colombia cycling is a national passion and Soler’s story is typical of his nation’s sparse but illustrious record in the Tour’s mountain stages. “I was 16 years old when I started to ride a bike,” he said at the finish yesterday. “My first ambition was to ride the Tour and win a stage, but I never thought it would come true. My team had confidence in me. They brought me to the Tour and now I have paid them back with my victory.”

Soler, who revealed that he had not previously raced over the Galibier, admitted that he had attacked like a maniac. “I had looked at the race guide, so I knew the Galibier was hard and I have fulfilled a dream. My family in Colombia is poor and everyone either works in the fields or is a farmer. It was always a dream to become a professional cyclist, so this is the biggest moment in my life.”

Behind the Colombian, high on the slopes of the Galibier, the poker game between the Tour favourites continued. With more than a dozen riders touted as a Tour winner at yesterday’s stage start in Val d’Isère, the tension grew until a decisive attack from Alejandro Valverde, of Spain, split the main group of riders, six kilometres from the summit.

Valverde’s initiative created a selection of six riders, now within three minutes of each other in the overall standings, who appear to be the main contenders for victory in this year’s Tour. In the Spaniard’s wake came Michael Rasmussen, the race leader from Denmark, Iban Mayo and Alberto Contador, also of Spain, Cadel Evans, of Australia, and, belatedly, Christophe Moreau, of France.

Yesterday, Moreau failed to revisit the dynamic attacking form that had so galvanised French fans in Sunday’s summit finish in Tignes. The 36-year-old struggled to limit his losses at the finish line to Valverde, by far the canniest rider in the leading group.

Despite slipping farther behind Rasmussen, Moreau remained defiant. “I always had confidence in myself,” he said. “I managed to cope with the attacks on the Galibier and as soon as a gap opened up, the others tried to distance me, but I only dropped a few seconds.”

Far worse befell Alexandre Vinokourov, the pre-Tour favourite, who was again unable to follow the key attacks and dropped farther in the standings, to 21st overall, and arrived in Briançon in tears. “Today was very difficult and now I have to reconsider everything, but I will keep fighting,” the Kazakh said. “The team worked hard, but it was an ordeal.”

The Spanish challenge appears strong, with Valverde and Contador repeatedly forcing their rivals on to the back foot. Contador, the winner in March of the Paris-Nice race, is only 24, but yesterday his accelerations were reminiscent of Marco Pantani, the Italian who won the 1998 Tour.

“Alberto has that explosive acceleration that can make a big difference in a short time,” Johan Bruyneel, the manager of Contador’s Discovery Channel team, said. “He saw that some of the favourites were struggling and attacked, which was a smart move. But we still have the time-trials and the Pyrenees to come and it’s a very close race.”