American Lance Armstrong effectively sealed a record seventh Tour de France victory, clinching his first success in this year's race when he won the penultimate stage on Saturday.
Six-times Tour winner Armstrong retained the overall leader's yellow jersey, comfortably beating off Germany's Jan Ullrich, who finished second 23 seconds behind in the demanding 55.5-km time trial around St Etienne.
Ullrich's team mate Alexander Vinokourov of Kazakhstan came home third.
"It's a great day, Lance wanted this stage badly. It was a hard course," said Armstrong's manager Johan Bruyneel
Ullrich, who was fourth overall before the start, leafrogged Michael Rasmussen to third place and looks set for a seventh podium finish in the world's most popular stage race.
Dane Rasmussen, the holder of the polka dot jersey for mountain specialists, had a nightmarish stage, suffering two falls and changing his bike three times.
He dropped to seventh overall after finishing 77th, more than seven minutes behind Armstrong.
Italian Ivan Basso, who came home in fifth, retained his second place in the overall standings.
Sunday's final stage will take the pack over 144.5 km from Corbeil-Essonnes to Paris.
