Ullrich's teammate Bjarne Riis of Denmark retained the overall leader's yellow jersey, but visibly weakening after his efforts over the past three weeks lost 2minutes and 18seconds to Ullrich -- to hold an overall lead of just one minute and 41 seconds over Ullrich going into the final stage.
Ullrich beat Spain's Miguel Indurain time by 56 seconds with another Spaniard Abraham Olano, runner-up to Indurain in the World Championship time-trial last year, third two minutes and six seconds in arrears.
The 22-year-old German was paid the ultimate compliment by Indurain, the five-time winner, who said that he would undoubtedly win a future Tour de France.
"He is as strong as an ox and his performances in the mountains and in the time-trials makes him a definite winner, as long as he stays fit," Indurain, who had earlier posted the target of one hour 16 minutes and 27 seconds, said.
Ullrich, red headed and with an earring in his right ear, was flattered but astonished at his performance in the stage.
"I am very surprised as I thought the times would be closer. As for Miguel's statement I am very touched but I will rest after the Tour and think things over," Ullrich, who gave up a place in the German Olympic team to ride in the Tour, said.
Riis, who discarded his helmet early on in the time-trial because of a pain in his neck, really struggled and displayed none of the energy that he had shown in the earlier stages.
"I don't know what happened but maybe my head was elsewhere -- like in Paris!" Riis joked referring to Sunday's traditional finish of the Tour in Paris.
As with Ullrich's other Telekom teammates Riis was quick to praise his young teammate.
"Jan was brilliant really magnificent and its great reward for all the work he did for me this Tour," Riis said.
Telekom have won three titles this Tour, Riis the overall with Ullrich second, Erik Zabel the points winners green jersey and Ullrich the Fabio Casartelli young rider's title.
Richard Virenque, already winner of his third successive King of the Mountains, ensured he finished third overall to become the first Frenchman since Laurent Fignon in 1989 to earn a place on the podium.
"Its great to be on the podium but I still count my first stage victory as the greatest thrill of my life as the peloton chased me for 100km," Virenque said.
Indurain although happy with his performance still cast doubt on whether he would go to Atlanta to race in the Olympic time-trial. "Yes, I was happy but I am still not sure whether I will go. A holiday with my wife and my young baby is an attractive option," Indurain said.
Earlier Britain's Olympic and World Pursuit champion Chris Boardman had shown he was recovered fully from his earlier stomach troubles by posting a time of one hour and 18 minutes which gave him seventh place in the stage.
Working hard for Dane Bjarne Riis has not stopped the 22-year-old from Rostock, making his first appearance in the race, taking second place overall behind his leader in the Telekom stable.
When the Tour ends in Paris on Sunday, Ullrich should become the first German to make the podium since 1932, when Kurt Stoepl finished second.
But his superb win in Saturday's penultimate stage, a demanding time-trial over 63.5 kms from Bordeaux to Saint-Emilion, suggested he might go for more than just second place in the near future.
Even Miguel Indurain, often in a class of his own against the clock, was impressed.
``It's quite remarkable when you think that he has been helping Riis all the time,'' said the Spaniard, who had to settle for second place in the stage. ``He's still very young and he certainly looks like he could win a Tour, if not several.''
Ullrich, a former amateur world champion, had wanted to come on the Tour as early as last year, but team director Walter Godefroot said it was too early.
This year, he decided to miss the Olympics because he badly wanted to take part in the world's greatest cycle race.
``The German team had a special preparation programme for Atlanta and I just couldn't do both,'' he said. ``It looks like I made the right choice.''
Ullrich dismissed suggestions he would have done better if he had not had to help Riis.
``The team was so great because Bjarne was in the lead,'' he said. ``To see him do so well boosted our confidence and anyway, he was much stronger than I was in the mountains. He's got plenty of experience. I've still got a lot to learn.''
Riis suffered in the heat in the day's 63.5-km stage through classic vineyards from Bordeaux, and ended fourth, two minutes and 18 seconds behind his promising Telekom team mate.
But the 32-year-old from Herning, now 1:41 ahead of Ullrich in the overall standings, should nevertheless become the first Dane to win the world's greatest cycle race after Sunday's traditional final parade on the Champs-Elysees.
``I badly wanted to win that stage but I was not at 100 percent,'' he said. ``I don't know if it was a physical problem or a mental one but anyway I'm fourth and it's not too bad. I'll be in the yellow jersey in Paris and that's all that counts.''
Nobody could follow the pace set by Ullrich, who covered a demanding course in one hour 15 minutes and 31 seconds at an average speed of 50.443 kph.
Five-times Tour winner Miguel Indurain, who had already lost all chance of a record sixth win by suffering in the Pyrenees and the Alps, restored some pride by finishing second, 56 seconds behind Ullrich.
The once unbeatable Spaniard, who finished one place ahead of compatriot Abraham Olano but is only 11th overall, said he had still not decided if he would take part in the Olympics.
``My form was not too bad today but it was a tough Tour for me and at the moment I'm still hesitating about Atlanta,'' he said.
Ullrich, the revelation of this year's Tour, confirmed he would be a force to be reckoned with in the next few years with a superb performance. ``I'm surprised,'' said the 22-year-old from Rostock, who has concentrated on helping Riis through the Tour and had not previously won a stage.
``All I wanted to do was hold on to my second place overall and I didn't think I would win the stage. I started very strongly and I thought I might crack but I didn't.''
Richard Virenque of France retained third overall by taking seventh place in the time-trial, and Sunday's stage to Paris, which usually ends in a sprint, should bring no changes to the leading final standings.
Virenque should keep the king of the mountains' red polka dot jersey while German Erik Zabel should retain the green one as the points classification leader.
Riis, who has stamped his authority on this year's Tour the way Indurain used to, said he was very satisfied. ``I felt great,'' he said. ``I didn't have an off-day or if I did it was today and I still finished fourth. I'm delighted. My only regret is that I didn't beat Indurain at his best, but he'll be back I'm sure.''
Riis had a tough day today, finishing two minutes and 18 seconds behind Ullrich. He said he was trying to win the stage but just wasn't riding as well as usual. He must have been paying for the past few days' efforts, including those in stage 17 which gave Ullrich second place.
The latter, on the other hand, freshened up everyone by mastering this time trial in phenomenal fashion, beating no other than Indurain.
Indurain was impressive too, finishing second despite not having had good sensations. He said he would still have to think about going to Atlanta.
In second place overall after having given so much for his leader, Ullrich could be blase. But he isn't, at only 22. And neither is this beautiful Telekom team, despite five stage wins, two riders atop the overall standings and Erik Zabel's green jersey.
Ullrich just kept on amazing all those, including King Miguel, who sees him winning the Tour some day.
There was only one change in the overall standings, with Luc Leblanc jumping two places, to sixth, one second ahead of Piotre Ugrumov.
The Festina men kept riding strongly, placing three riders (Dufaux, Virenque, Brochard) in the top ten, consolidating their lead in the team standings. Best climber Richard Virenque kept his third place overall by faring surprising well - for a climbing specialist -and staying close to teammate Laurent Dufaux.