Since Armstrong returned to competition this year, they have ridden together only once in a race — the Vuelta of Castilla and Leon in March — but Armstrong crashed out of it with a broken collarbone.

“Everybody has been waiting for the Tour to see this meeting of Lance and me, and it gives me added motivation — and pressure, too,” Contador said.

Armstrong, once known as “Le Boss” of the Tour, can’t be ruled out for victory. But his training regimen has been unorthodox in part because of his family duties, glitzy personal life and charitable work in the battle against cancer.

“What do I expect from him? Really, I don’t know,” Bruyneel said. “We are a bit lost. ... Alberto knows he’s ready. Armstrong, we don’t know.”

As if cramming for a final exam, Armstrong spent Friday previewing the course but found time to keep in touch with his million-plus followers on Twitter.

“This place is going to be electric tomorrow,” he tweeted.