After a week of mostly flat stages won by sprinters, the Tour de France hits the mountains in Saturday's seventh stage, when the race standings are likely to be shaken up on the punishingly steep final climb to La Planche des Belles Filles.
The 3,395-foot summit in France's eastern Vosges mountains has never before been featured in the Tour's 109-year history, and it will likely be the occasion for the race-leader's yellow jersey to change shoulders for the first time since Swiss rider Fabian Cancellara captured it in the race's opening prologue a week ago.
The teams of Tour favorite Bradley Wiggins and defending champion Cadel Evans will likely take a more prominent role in the 123.7-mile hilly stage from Tomblaine to La Planche des Belles Filles, when climbers launch the inevitable attacks on the category-1 mountain.
Planche des Belles Filles is a 3.7-mile climb with stretches as steep as 14 percent. Roads that steep look to be almost vertical walls as they're approached. It's one of the new climbs Tour organizers included in this year's route, which Christian Prudhomme, the Tour director, calls "the steepest Tour ever."
Wiggins' Team Sky has ridden the climb in preparation for the stage, manager Dave Brailsford said.
"I think certainly we'll see some attacks and people trying to take their first opportunity to make some time differences," Brailsford said.
The standings got a first shuffle in Friday's sixth stage, caused by a massive crash that took out half the peloton with 16 miles to go. Sky's Edvald Boasson Hagen was delayed in that crash and dropped out of race's top 10, but the Norwegian champion said it meant nothing.
"My job is to work for Bradley, if I'm hours or weeks back, it doesn't matter," the 25-year-old two-time Tour stage winner told reporters outside his team bus after the race.
Wiggins' team had escorted him to the front of the pack mere minutes before the crash, thereby protecting his second place in the overall standings, seven seconds behind Cancellara.
The crash-induced shakeup in the standings also dealt a likely fatal blow to the yellow jersey aspirations of Giro d'Italia winner Ryder Hesjedal of Canada, who injured his left knee in the crash and now sits over 13 minutes back in 108th place.
That could mean extra fireworks when the race hits the mountains Saturday, Brailsford said.
"Some of the good climbing guys will think, `Well, I've got nothing to lose now, I've got to really animate the race and get something back," Brailsford said.
French rider Sylvain Chavanel, whose stage win at Station des Rousses in the 2010 Tour demonstrated his strength in steep finishes, agreed that the climb to Planche des Belles Filles will be key.
"(Saturday's stage) will be the first test for everyone for the GC because after a week without climbs, the first climb is always an important and demanding test," Chavanel said.
American rider Levi Leipheimer, Chavanel's teammate on Belgian squad Omega Pharma-Quickstep, said "it's definitely going to become clear who is strong, who the favorites are" after Saturday's stage.
Peter Sagan of Slovakia avoided a bloody, across-the-road pileup to capture his third stage win Friday, while Cancellara also steered clear of the mayhem to maintain the yellow jersey.
The 129-mile ride from Epernay to Metz began in the Champagne region of France, with roadside fans holding aloft glasses of bubbly to cheer the riders.
But as the pack picked up speed to chase four breakaway riders with about 16 miles to go, at least two dozen riders spilled across a rural road. Many were downed and dazed, looking for team staffers in a jumble of injured riders and bikes.
"It was like a trench hit by a (grenade) when I entered the crash to give my bike to Bauke," Rabobank's Laurens Ten Dam said on Twitter, referring to teammate Bauke Mollema. "Lots of blood and screaming. Carnage."
The U.S. Garmin-Sharp team bore the brunt of the crash.
Tom Danielson, who finished in last year's Tour in eighth place, was already nursing a separated shoulder from a crash earlier in the week. In Friday's spill, he was briefly knocked unconscious, and later rushed to a hospital for hip, collarbone and elbow injuries. He was one of at least four riders to drop out of the race because of the crash.
Garmin's Ryder Hesjedal of Canada - winner of the Giro d'Italia in May - injured his knee and lost more than 13 minutes, all but ending his chances for a top-three finish. He had started the stage in ninth place, 18 seconds back.