Ukraine's Serhiy Honchar grabbed the Tour de France leader's yellow jersey with a stunning victory in Saturday's stage-seven time trial.
Honchar set a blistering pace on the streets of Rennes
The T-Mobile rider clocked 1:01:43.6 for the 52km test in Rennes to beat American Floyd Landis by 61 seconds.
Germany's Sebastian Lang was three seconds slower, while Briton Bradley Wiggins was 28th and David Millar 37th.
American Bobby Julich crashed out of the race after falling, while contender Levi Leipheimer lost six minutes.
A third American to struggle was stage favourite David Zabriskie, who ended 13th, 1:57 behind, while compatriot George Hincapie, of Lance Armstrong's old Discovery Channel team, trailed home 2:42 back.
Australia's three-time world time trial champion Michael Rogers, who also rides for T-Mobile, was fourth and climbed to third overall, eight seconds behind Landis and 1:08 adrift of team-mate Honchar.
The 36-year-old Honchar, world time trial champion in 2000, is the first Ukrainian rider to wear yellow in the Tour. It was his first stage win in three Tours de France, while he has won five time trials at the Tour of Italy.
It was pretty important for the team because we have been through some difficult times
"I am extremely happy," said Honchar. "Time trials are my speciality, I did my best and I have done pretty well - I succeeded in the end.
"It was pretty important for the team because we have been through some difficult times. I am very happy to get the victory, and of course the yellow jersey."
The T-Mobile team, robbed of leader Jan Ullrich on the eve of the race after a doping investigation, finished with six riders in the top 20.
"Everybody did it the way we planned," said T-Mobile technical director Mario Kummer.
"Serhiy started fast and was able to maintain his rhythm. We are not surprised, Serhiy has proved in the past that he is a specialist in time trials. He rode a good stage today, he is very strong."
Belgian Tom Boonen, who wore yellow for the previous three days, finished 41st, 3:52 off the pace, and slipped to 21st overall.
Sunday's stage eight is another relatively flat run of 181km from Saint-Meen-le-Grand to Lorient in north-west France.
After a rest day on Monday, the riders enter the Pyrenees on Wednesday when the real contenders for overall glory will surface.
Results from stage seven:
1. Serhiy Honchar (Ukr/T-Mobile) 1:01:43
2. Floyd Landis (USA/Phonak ) +1:01
3. Sebastian Lang (Ger/Gerolsteiner ) +1:04
4. Michael Rogers (Aus/T-Mobile ) +1:24
5. Gustav Erik Larsson (Swe/Francaise des Jeux) +1:34
6. Patrik Sinkewitz (Ger/T-Mobile) +1:39
7. Markus Fothen (Ger/Gerolsteiner) +1:42
8. Andreas Kloeden (Ger/T-Mobile) +1:43
9. Denis Menchov (Rus/Rabobank) +1:44
10. Joost Posthuma (Ned/Rabobank) +1:45
28. Bradley Wiggins (Gbr/Cofidis) +3:10
37. David Millar (Gbr/Saunier Duval) +3:34
1. Serhiy Honchar (Ukr/T-Mobile) 30:23:20
2. Floyd Landis (USA/Phonak) +1:00
3. Michael Rogers (Aus/T-Mobile) +1:08
4. Patrik Sinkewitz (Ger/T-Mobile) +1:45
5. Markus Fothen (Ger/Gerolsteiner) +1:50
6. Andreas Kloeden (Ger/T-Mobile )
7. Vladimir Karpets (Rus/Caisse d'Epargne) +1:52
8. Cadel Evans (Aus/Davitamon-Lotto)
9. Denis Menchov (Rus/Rabobank) +2:00
10. David Zabriskie (USA/Team CSC) +2:03
25. David Millar (Gbr/Saunier Duval) +3:38
147. Bradley Wiggins (Gbr/Cofidis) +17:55