Spain's 2007 champion Alberto Contador of Astana took possession of the Tour de France yellow jersey after a superb solo attack and victory on the 15th stage in the Swiss Alps on Sunday.
Contador, winning his first individual stage of this year's race, attacked a small group of favourites containing teammate Lance Armstrong 5.6km from the summit of the 8.8km climb to the summit finish of Verbier.
The Spaniard's move shook up the favourites, and dropped Australian Cadel Evans and defending champion Carlos Sastre of Spain further down the overall standings.
Luxembourg's Andy Schleck was the only rider to counter Contador's move, but the Saxo Bank leader's effort was in vain.
"He went off like a rocket," said Schleck, who limited his losses to finish line 43secs behind in second place and is now fifth overall at 2:26.
Seven-time champion Armstrong lagged in at 1:35 behind, only a handful of seconds behind two-time race runner-up Evans, who was at 1:26.
Contador now leads Astana teammate Armstrong by 1:37 in the overall standings, with Briton Bradley Wiggins of Garmin, continuing to impress, in third at 1:46. German Andreas Klöden, also of Astana, is fourth at 2:17.
"I'm very happy with this result," said Contador, who since the start of the race has had to endure the extra pressure of Armstrong's presence in the team. "It wasn't a long climb, but we started it really fast and in the end I managed to do what I wanted to make the difference.
"If I wanted to leave my rivals behind me in the standings, that was the only way I could do it."
Armstrong admitted he was "on the limit" as early as the bottom of the climb and from then on had little else to give.
But after admitting Contador was the better man on the day, the American now appears ready to give the Spaniard his full backing.
"There is no point messing around. I gave everything I had and I wasn't the best," said Armstrong. "I'm gonna do my best and be a solid teammate."
Armstrong and Contador during the stage
The early breakaway included Fabian Cancellara, Mikel Astarloza and Pierrick Fedrigo
After a week of uninspiring racing the 15th stage finally lived up to its billing as a crucial player in the yellow jersey battle. After the last remnants of a 12-man attack were reeled in early on the 8.8km climb to Verbier, the big contenders took centre stage.
Andy Schleck's older brother Frank first tested the resolve of Contador and Armstrong with a brief attack which left defending Sastre quickly trailing. And moments later the Spaniard was given more food for thought when Contador emerged from the maelstrom of an eight-man group to pull away with apparent ease.
After a brief hesitation, Andy Schleck counter-attacked but struggled to match the Spaniard's pace.
Franck Schleck prepares to attack Contador, Armstrong, Andy Schleck and Wiggins
Behind, Sastre had managed to join Armstrong's group, from which Wiggins, the Olympic pursuit champion, had accelerated to take Frank Schleck and Italian Vincenzo Nibali with him.
In their wake an acceleration by Sastre prompted Evans to follow, and that move left Armstrong and Klöden on their own to finish the race together, the German coming over the finish a few seconds in front.
Andy Schleck warned Contador he would be calling on Saxo Bank to help him erode the Spaniard's advantage in the coming days in the Alps.
"That wasn't a great mountain stage, once we get the accumulation of several climbs, that when we'll see big differences, it will be an interesting last week," said Schleck.
Evans, the runner-up the past two years, now looks well out of contention in 14th at 4:27 adrift, but the Australian was upbeat after admitting it was "possibly one of the worst days of my Tour de France career".
"Sometimes you just have to do what you can and I don't know about the time loss and the placings, but I think I defended well for a guy who was having a horrible day," said Evans.
Sastre, who is now 11th overall at 3:52 behind, spoke for most of the peloton when he said: "Obviously, there's one rider above all the rest here and that's Alberto Contador.
"I want to congratulate him for his victory, it was stunning. Behind him, we're all at about the same level."
© AFP 2009
For full results, report and photos, visit Cyclingnews.com.
You can follow BikeRadar on Twitter at twitter.com/bikeradar.