Armstrong once more outdid his rivals

Afterwards Boogerd hailed it as the "biggest win of my whole career"

He added: "And it makes it even more special that it's the most difficult on the Tour."

The stage win was some consolation after struggling to live up to his early promise.

The Dutch rider's 1996 stage win and his highest place of fifth overall saw him billed as a future Tour de France winner.

But the 30-year-old has been plagued by off days in the mountains in recent seasons and conceded the race leadership to team-mate Levi Leipheimer ahead of this year's race.

Armstrong's third place virtually assured him of a fourth Tour de France victory as he pulled out a further 40s on Joseba Beloki and Raimondas Rumsas, second and third respectively in the race overall.

He now leads the race by more than five minutes and, barring injury or illness, will take victory in Paris at the weekend.

The US Postal rider said: "It was really a difficult stage. La Plagne is a tough mountain pass. It's a complicated day. It's never flat."

Botero burst

Once again the early part of the stage was littered by breakaways.

Santiago Botero, winner of Tuesday's 15th stage, made the first serious attempt on the day's opening climb.

But that failed and it was left to Boogerd to break on the descent of the Col du Telegraphe after 45km.

A group including Axel Merckx, King of the Mountains leader Laurent Jalabert and Miguel Martinez tried to close the gap but were eventually sucked back into Armstrong's chasing group.

Boogerd maintained an advantage of five minutes at the base of La Plagne, the final ascent of the 179.5km stage, but looked to be tiring in the final stages as Sastre and Armstrong reeled him in.

But the Dutchman managed to do enough to stay in front.

The stage saw yet another big name fall by the wayside as Oscar Sevilla retired with stomach cramps.

David Millar had another difficult day in the saddle and was 34m26s off Boogerd's time. He is now 69th overall.