The CSC team finished two seconds behind after yellow jersey wearer David Zabriskie fell in the last 2km.

Zabriskie trailed in behind the rest of his team and is now more than a minute adrift of six-time champion Armstrong.

Another American George Hincapie is second in the overall standings, 55 seconds behind his team-mate.

CSC looked to be on target for the stage win on the 67.5km stage from Tours to Blois before Zabriskie's tumble.

The American's team were two seconds ahead of Discovery Channel after 61.5km but Zabriskie fell in the middle of the pack causing CSC to lose precious seconds.

Jan Ullrich and his T-Mobile team took third, 35 seconds behind Discovery Channel, while Liberty Seguros took a surprise fourth.

Phonak were one minute and 31 seconds off the pace in fifth.

Stage four team-time-trial result:

1. Discovery Channel 1hr 10mins 39secs
2. Team CSC +2secs
3. T-Mobile +35
4. Liberty Seguros +53
5. Phonak +1:31
6. Credit Agricole +1:41
7. Illes Balears +2:05
7. Gerolsteiner +2:05
9. Fassa Bortolo +2:19
10. Liquigas +2:26
11. Davitamon - Lotto +2:32
12. Rabobank +2:48
13. Domina Vacanze +3:04
14. Quick-Step +3:05
15. Bouygues Telecom +3:08
16. Euskaltel +3:59
17. Lampre - Caffita +4:09
18. Cofidis +4:28
19. Francaise des Jeux +4:46
20. Saunier Duval +5:06
21. AG2R +5:23

Overall standings:

1. Lance Armstrong (US/Discovery Channel) 9hrs 59mins 12secs
2. George Hi