Leipheimer is 31 seconds behind in third place.
Leipheimer won Saturday’s 56km time trial from Cognac to Angouleme in a time of 1 hour, 2 minutes, 44 seconds.
"I have always dreamed of winning a stage of the Tour de France, either a mountain stage or a time trial," Leipheimer said after the stage.
"I think my emotion took over [at the end], and I went faster and faster."
Should Contador hold onto his lead he would be the Tour's youngest winner since Jan Ullrich in 1997.
A victory for Evans would be a huge lift for cycling in Australia, where the sport remains largely on the fringes despite their regular production of Olympic and World Champions.
The battle between Contador and Evans brought some much needed focus back onto the cycling for the besieged race, after three riders were kicked out in the space of 30 hours, two for doping, and one for lying to his team
|Contador took the overall lead only after |
Rasmussen was expelled by his team [AFP]
The race has been reeling from Wednesday's withdrawal of race leader Michael Rasmussen, as well as other drug-related episodes.
Contador took the overall lead only after Rasmussen was expelled by his Rabobank team for lying about his whereabouts when he missed a doping check last month.
German rider Patrik Sinkewitz, Italy's Cristian Moreni and pre-race favorite Alexandre Vinokourov were all ejected after testing positive for doping.