Four-time champion Lance Armstrong seized the initiative after a third-placed finish in the gruelling 219-km eighth stage of the Tour de France from Sallanches to l'Alpe d'Huez.
The American, winner in the skiing resort in 2001, had to leave stage victory to Basque Iban Mayo, his leading rival in the recent Dauphine Libere race, who won in just under six hours. Alexander Vinokourov of Kazakhstan was third.
But the Texan, 2:12 behind Mayo, relieved Frenchman Richard Virenque of the race leader's yellow jersey after the Quick Step rider was dropped in the 21 corners leading to the top of the hill.
Armstrong, who is bidding for a record-equalling fifth victory, leads for the first time in this Tour, but he was seriously tested by his rivals in the 14 km of the final climb, lined by hundreds of thousands of spectators.
Mayo made his move eight km from the finish, while Armstrong was repeatedly held back by Basque Joseba Beloki, second last year, and by the injured American Tyler Hamilton, impressive after breaking his collarbone in the first stage.
With the help of his US Postal team mates, then on his own, Armstrong managed to limit the damage, but for once did not crush the opposition in the decisive mountain stage as he did in his four previous victories.
The American will lead the field back into the valley tomorrow for the 184.5-km stage to Gap.