When it came, the passing of the baton was dramatic, decisive and clinically executed. Unfettered from team duties, unshackled from his own insecurities, Jan Ullrich flew upwards, devouring the remaining kilometres and destroying the opposition.

For days he had played the role of loyal henchman to perfection; protecting team-mate Bjarne Riis from the wind, pacing him on climbs and unselfishly, holding back when there was any sign of weakness. He was young, Riis was defending champion and his chance would come again.

But two days in the mountains of that 1997 Tour proved team Telecom's number one was playing with a dud hand. Out of the saddle, mouth open and sweat pouring off his bald pate, Riis' laboured style was in stark contrast to the flowing, powerful pedal strokes of Ullrich. There was only one decision open to team Directeur Sportif Walter Godefroot.

Set free, Ullrich motored. His acceleration was savage, shattering the unity of the group behind and scattering exhausted riders over the Arcalais climb. Multiple king of the mountains Richard Virenque was the last to crack, but crack he did; by the finish, he and gifted grimpeur Marco Pantani had conceded a massive one minute and eight seconds in just over five kilometres. And more was to come in the following days.

Crushing the field in that 1997 Tour de France, Ullrich's phenomenal talent was obvious. The wunderkind had shocked all by finishing second in his Tour debut 12 months previously; now, winning the race at 23 years and seven months echoed similar achievements by quintuple victors Bernard Hinault and Jacques Anquetil. It had taken the great Eddy Merckx even longer to begin amassing his five trophies.

Did we have a new Cannibal? "I think we are going to see one hell of a lot of him after "He is the new champion that we are going to have for a decade. If he doesn't make any mistakes and steers his ship well, he'll be there (in yellow) until 2003 or 2004."

Most of Germany concurred. "Jan is going to be a big, big champion", was the common sentiment. How right they were. But not in the way they envisaged.

Later today Jan Ullrich will burst down the starting ramp to begin his 2001 Tour de France campaign. The streets of Dunkirk are the venue for this prologue time trial of 8.2 kilometres; 10 minutes of flat-out, lung-busting effort which provides an early indication as to who is hot and who is not.

Mere seconds will separate the top riders after this short test, but beating double Tour champion Lance Armstrong is a priority. The first salvo in a ferocious three-week battle.

Rebuilding. It is four years from that day in Andorra and things haven't quite gone to plan. Hinault was just one of many experts who predicted a succession of victories, but instead the so-called Tourminator faltered under the pressure of new-found stardom. Calling a halt to his 1997 season shortly after that Tour win was a warning sign. Becoming increasingly reclusive and amid heightened speculation that all was not right, a bloated Ullrich emerged for the new season 12 kilos overweight. Hinault et al were quick to change their tack. "If Ullrich arrived in Dublin ready for the Tour, I'll take my hat off to him," the Frenchman proclaimed dismissively.

Cue a panic-stricken Telecom team. Crash-diets and below-par performances often saw Ullrich trail in 15 or 20 minutes behind the bunch in hilly races. It is tribute to his massive talent that he bounced back to seize yellow in the 1998 Tour and eventually finish second overall behind Marco Pantani.

"Next year will be different," vowed Ullrich, the stings of criticism exceeded only by the pain of losing. Yet once again things went astray; a love of cakes overcame his good intentions, a run of poor health frustrated his plan to race himself into shape. Then, a crash in the Tour of Germany resulted in a knee injury which removed him from the 1999 Tour de France.

Back to the drawing board. The knee healed, he regained something approaching top shape and won the Tour of Spain and the world time-trial championship. But still the roller-coaster ride continued; weight and health problems loomed again last spring and, climbing poorly, another second place in the Tour de France followed. Gold and silver medals in the Olympic road race and time trial came on the upswing and further heightened talk of how good he would be if he could just get it together for the Tour.

Meanwhile, Lance Armstrong had emerged as the new dominant force in world cycling. The Texan recovered from testicular cancer to win both the 1999 and 2000 Tours, ironically seizing the titles in a manner almost identical to Ullrich's victory. Both strong time triallists, both all-rounders suited to three-week stage races, the parallels extend yet further. When Armstrong took gold in the professional world championships in Oslo in 1993, the then 19-year-old German won the amateur crown. And both saw their fathers walk out of their lives at an early age, a factor which some feel has cultivated their huge ambition.

The similarities have led to a mutual respect. Armstrong is quick to laud Ullrich's talent, identifying him as his biggest rival in the Tour de France, while the German describes the Texan as "a great champion". Riders like Joseba Beloki and Christophe Moreau (third and fourth last year) may be going into this year's race in great form, but the two past winners see this as essentially a two-horse race.

But there is a crucial difference between two - discipline. While Ullrich's past three seasons have been a tale of rushed preparation, Armstrong has been meticulous in his approach. Reaching the Tour in immaculate condition is the priority and so the 29-year-old spends weeks training over the climbs of the Tour each spring. He goes as far as to weigh his food, calculating exact calorific requirements so that he starts the Tour with a minimum of body fat. "Bulimic in his appetite, anorexic in appearance," wrote a French journalist last year. The difference is Armstrong's hunger is for success rather than more customary sustenance.

To his credit, Ullrich has had the best preparation since his 1997 victory.

He has raced for much of this season (albeit rather anonymously) and in June completed the three-week Tour of Italy in order to gain the condition he needs this month. Since then, long training rides in the Alps and Pyrenees have honed his fitness and reduced his weight.

"I did everything that I had to in order to be ready," he said in recent days. "I feel strong and I have a strong team around me." Indeed the entire team is geared towards Ullrich's Tour bid - quintuple green jersey winner Erik Zabel starts the race without his trusted lead-out man Gian-Matteo Fagnini, a move which threatens his bid to take a sixth straight points victory. And the poaching of Armstrong's former right-hand man Kevin Livingston from the US Postal squad is a big coup.

Things are coming together. Last weekend Ullrich rode impressively to take the German national road race championship, dropping Zabel in the closing stages to finish alone. He last won the title before his successful campaign four years ago; that statistic gives him great encouragement. "The champion's jersey brought me luck in 1997," he said. "And I am a little superstitious."

According to Godefroot, Armstrong's domination of the Tour of Switzerland means he may have the edge for the first few days, but he expects his star rider to reach peak form before the mountains. "Both will fight at the same, very high level." It is going to be an enthralling contest.

Enthralling, that is, provided the race doesn't come apart at the seams. The drug bust during the Tour of Italy has shown that three years after the scandal-struck 1998 event, some riders continue to dip into the medicine cabinet. Police raids are anticipated during the Tour and the prospect of more unsavoury news is always a possibility. Drug testing - such as the recent measure to detect EPO - has improved considerably, but there is still room for manipulation.

To his credit, race organiser Jean Marie LeBlanc has made great efforts to address the problem. Earlier this year he introduced a 10-point plan to reduce doping; more recently, he has said that any team which returns a positive test will be removed from the race. So, too, any squad which is proven to have sinned in the Italian Tour.

Both Armstrong and Ullrich go into the race with this Damoclean Sword hanging over them. The US Postal team is the subject of an ongoing, unresolved French inquiry into alleged malpractice on the team, while an asthma inhaler belonging to the German was seized during the Tour of Italy raid. He says he had medical clearance to use the product; Armstrong has welcomed the analysis of blood samples taken from his team in last year's Tour. "We have nothing to hide, and this analysis will prove it," he said.

Both riders have, in recent weeks, called for life bans for those proven to be guilty of doping. Arrogance, or innocence? As we watch their Herculean clash over the next three weeks and follow Ullrich's bid to once again wear yellow to Paris, we pray for the latter explanation. Otherwise the sport will take a body blow from which it may never fully recover.