In one of the biggest upsets in the Tour's recent history, the Spaniard Oscar Pereiro has retaken the yellow jersey after the race leader Floyd Landis suffered a spectacular collapse on the stage's final climb yesterday.
Ten kilometres from the summit finish at La Toussuire, the stage win was all but guaranteed for the Dane Michael Rasmussen, whose long lone break also regained him the lead in the King of the Mountains competition he won last year.
But it was the fight for the yellow jersey and the utterly unexpected twist when Landis slid out of a group of a dozen pursuers, and ultimately out of the battle for victory in Paris, that raised tension to electric levels.
His head sagging from side to side, sweat pouring from his forehead, Landis' demise was as dramatic as it was utterly unexpected.
Not since Jan Ullrich in 1998, when the German suddenly lost the plot on the Col du Galibier in the face of Marco Pantani's searing attacks and lost 10 minutes, has the maillot jaune been in such trouble on a mountain stage.
Ahead, T-Mobile quickly took control but they were unable to help their leader, Andreas Klöden, to shake off Pereiro. Even when the 2004 Tour runner-up accelerated in person, the Caisse D'Epargne rider stuck to his back wheel like glue, with Australian Cadel Evans also in close contact.
The trio crossed the line together, allowing Pereiro to return - against all expectations - to yellow, with fellow Spaniard Carlos Sastre moving up to second overall, 1min 50sec back.
"I felt very good today, but I knew that my only chance of returning to yellow was if Floyd cracked." Pereiro admitted. "Yesterday [Tuesday] he was the strongest rider in the race, today he suddenly lost it all. It was an incredible turnaround.
"I don't know if I can win the Tour," he added, "but I've certainly taken a very big step towards doing so."
Pereiro is perhaps wise to be cautious: yesterday was the ninth change of yellow jersey in the 2006 Tour - a record - and so far the race has proved anything but predictable.
Twice 10th in the Tour, the Spaniard lost nearly half an hour in one Pyrenean stage to Landis and only moved back into the frame on the 13th stage after Landis' team, Phonak, allowed him to take over in yellow as a tactical manoeuvre to save their collective strength.
On Alpe D'Huez, where Landis recovered the lead, it looked as if Phonak's calculated gamble had paid off. Now, however, their strategy looks as if it could catapult Pereiro into yellow in Paris.
Landis trailed in 10 minutes behind, his battle for overall victory finished, and the race comes down to a three-way struggle between Sastre, Pereiro and Klöden.
Pereiro is now favourite, but Sastre could make a move on today's final Alpine stage, while Klöden's best chance will come in Saturday's time trial.
l The world road race champion Tom Boonen, who won a stage of the Tour of Britain in 2004, will ride in this year's event, which starts next month.
Alasdair Fotheringham writes for 'Cycling Weekly'Reuse content