The Tour de France is no longer sacred as an institution and it may have lost much of its credibility but it has retained its ability to tug at the heartstrings.

The weekend belonged to the American Lance Armstrong, who won the prologue time-trial at Le Puy du Fou on Saturday and spent yesterday resplendent in the yellow jersey as the peloton sped through the rain-soaked lanes of the Vendee.

Yesterday's bunch sprint finish, won by the Estonian champion Jaan Kirsipuu, did not threaten his lead and he will wear yellow again today as the race moves north into Brittany to the port of Saint Nazaire.

In the Tour's 96-year history there have been few stories as romantic as Armstrong's tortuous comeback from testicular cancer. He was one of cycling's most precocious talents, winning the world championship and a stage in the Tour before turning 23, but his career was widely assumed to be over when the illness was diagnosed in September 1996.

After operations on his abdomen, lungs and brain, and intense chemotherapy, from which he still bears the scars, he embarked on a voyage into the unknown when he decided to return to cycling at the highest level. No endurance athlete had ever attempted such a feat after cancer of such severity; the Texan had to overcome his own fears of a relapse and the scepticism of teams unwilling to risk hiring a potential invalid.

The French press have made much of the fact that Armstrong now spends a lot of the year in Nice, together with his wife Kristin - who is expecting their first child - and a white cat which he has nicknamed Chemo. However, the Texan has never forgotten that it was a French team, Cofidis, which attempted to renegotiate his contract - downwards - while he lay in a cancer ward and that one of France's top team managers replied to Armstrong's requested salary after his comeback with the comment "but that's a champion's wage".

The American will never forgive French cycling for the way it treated him when he was down but his love affair with the Tour has lasted six years, beginning when he rode the prologue time-trial in 1993, on the same course where he took the yellow jersey on Saturday. A feisty stage win at Verdun followed that year, and two years later came the moment Armstrong still describes as the most emotional of his career: the victory at Limoges when he pointed his fingers to the sky in tribute to his team-mate Fabio Casartelli, who died in a crash on a Pyrenean descent a few days earlier.

Fourth place in last year's Tour of Spain convinced Armstrong he had the ability to last three weeks, so he has built his whole season around the Tour. His US Postal Service team - American funded, managed by a Dutchman and a Dane based in Barcelona and made up of Danes, Frenchmen and Americans - placed four other riders in the first 20 on Saturday and looks strong enough to back him in his bid for a place on the podium in Paris.

The messages from the roadside were ambiguous. In contrast to the throngs of six years ago the French public was not out in force, as might have been expected on a Sunday in one of the country's most popular holiday areas, but that could have been put down to the wet weather.

The placards in support of the Tour's darling turned black sheep Richard Virenque were cancelled out by those proclaiming he was not welcome.

This Tour will remain on a knife-edge "between redemption and chaos", as one French newspaper put it yesterday, all the way to Paris. On Saturday afternoon the difference between credibility and lack of it came down to the seven seconds by which Armstrong beat Alex Zulle, one of last year's disgraced Festina nine and now definitely a favourite. In the morning it depended on the fractions of a percentage point by which one cyclist scraped past the blood test intended to counter the use of erythropoietin.

There were further drug revelations at the weekend - EPO discovered at the home of Gianluca Bortolami, winner of the World Cup in 1994, anabolics found in the house of a team manager in Italy.

Also over the weekend a leading German doping expert said he had given information to an official police inquiry into systematic doping among cyclists, including members of Team Telekom.

Werner Franke, a doping expert from Heidelberg University, said a state prosecutor in Germany was investigating the sport, including members of the Telekom team. He did not specify which individuals were being investigated.

"It involves a state prosecutor in the Rhineland, which is examining the area of nutrition. I gave the investigators documents showing how material from Belgium was received by top German cyclists," Franke said on NDR4 radio.

So far, however, the show is still on the road.