Spain's Iban Mayo won stage eight of the Tour de France after a powerful surge up to the finish in the ski resort of L'Alpe d'Huez.
Mayo, 25, attacked four-times Tour winner Lance Armstrong on the lower slopes of the famous climb to secure his first stage win.
And Team Telekom's Alexandre Vinokourov finished second, one minute 44 seconds adrift on the brutal 219-km stage from Sallanches which crossed the 2,645m Col du Galibier.
Armstrong won a sprint to the line to finish third, 2:11 behind Mayo but sufficiently far ahead of overnight leader Richard Virenque to assume the overall race lead.
There was purpose in his final push to the line.
The American had not looked at his strongest all day and was duly subjected to attack after attack from his key rivals.
But, although he was forced to concede the stage to Mayo and a small amount of time to Paris podium-contender Vinokourov, Armstrong kept the likes of Tyler Hamilton and Joseba Beloki at bay.
And he reduced the threat of German Jan Ullrich, who finished more than three and a half minutes off the pace.
Afterwards, Armstrong admitted that it had been a challenging day in the saddle.
"Everybody attacked today," he said.
"Beloki's attacks did a lot of harm. Mayo's were less important as he was far behind in the overall standings and is not so good in time trials.
"But it was hard, a very difficult stage. The team was superb, as for me, I'm not too sure. I did not have the best sensations, the best legs, and
it was no bluffing.
"I did not feel too well on the Galibier and from that point, it was my decision to ride a conservative race. I
decided to let Mayo go and to control Beloki."
The peloton had clicked into top gear from the very start on another baking-hot day in France.
The first meaningful gap was opened by Nicolas Portal, Pierrick Fedrigo, Franck Renier and Axel Merckx, who had made clear his ambitions for the stage.
But the US Postal team of Armstrong upped the pace on the Col du Telegraphe and swept up the breakaway before the Tour's first "hors category" climb up to the Col du Galibier.
Italy's Stefano Garzelli won the sprint to the top of that mountain, after riding away from a 30-man pack featuring all the key contenders.
But the major drama was reserved for the Alpe d'Huez.
A US Postal move shook off Virenque and Ullrich but not CSC team leader Hamilton, despite his broken collarbone from a crash earlier in the week.
Then Armstrong's team were hit by a surge from Beloki.
Armstrong responded and took with him Hamilton and Mayo to join the Spanish ONCE leader.
But, no sooner had the lone breakaway been reeled in than Mayo set off up the road on his own.
With Mayo a distant threat to the overall classification this year - albeit a bright hope for future Tours - Armstrong was happy to let him slip away.
And the US Postal supremo kept a close eye on Vinokourov to ensure his change from blue jersey to yellow.
Monday's 184.5km stage travels from Bourg d'Oisan to Gap over the hors category climb of the Col d'Izoard.