With three days of tough climbing to nearly 3000 metres in altitude, the four or five main contenders will have their work cut out on some of the legendary climbs which have etched pain on the faces of thousands of riders.
The Col d'Izoard, the Alpe d'Huez, the Galibier and Joux Plane are among the race's most popular climbs with the fans, and the most feared by the peloton.
But for the first time in eight years, the spectacular backdrop of the famous mountains should host a more dramatic battle for the race's main prize.
Since Armstrong's retirement last year, no team has taken command of the race's peloton the way he and his Discovery Channel teammates did in their seven-year reign.
And that means American Floyd Landis, Russian Denis Menchov, Germany's Andreas Kloden and Cadel Evans of Australia will have to express their climbing skills to the full if they are to stay in contention.
Talk of strategic alliances has been mentioned in the days leading up to the Tour's big rendezvous, which will be followed by another potentially decisive time trial on stage 19.
But the likelihood of a show of collective strength - whether individually or with others - on soul-destroying climbs with gradients of up to 11.5 percent appears remote.
"No one has stamped their authority on this race. It's going to be crazy in the next few days," said Britain's David Millar.
Davitamon team manager Hendrik Redant, whose star climber is Evans is among the big favourites, said it's every man for himself.
"There's going to be four or five guys who fight for it man to man. I don't think the teams are going to be involved," he said.
In the Armstrong era, his team was known for setting a steady but fast pace on many of the race's more difficult climbs.
Attacks by teammates who had been hand-picked for the job often caused chaos and in the end their collective effort proved too much for many of their rivals.
Even when his teammates found the going too tough, Armstrong normally had enough in reserve to drop his main rivals on the final sections.
Even when team tactics are used, they don't always work.
T-Mobile's efforts to imitate Armstrong on the race's 11th stage in the Pyrenees almost killed off all their yellow jersey hopes.
Having managed to drop a few contenders, Michael Rogers and Andreas Kloden then failed to follow five stage leaders when Dutchman Michael Boogerd upped the pace for his Rabobank teammate Menchov on the fifth and final climb of the day.
Tuesday's 15th stage is a 187km ride from Gap to the Alpe d'Huez. The Col d'Izoard is a 14.2km climb at an average of seven percent.
The descent is followed by the 12.1km ascent of the Col du Lautaret, which at 4.4 percent should be a little kinder on the legs.
The 13.9km climb to the summit finish of the Alpe d'Huez, whose 21 famous hairpin bends count down backwards, begins with a punishing two kilometres at 10 percent.
It evens out slightly before then hitting a one-kilometre long section at 11.5 percent four kilometres from the summmit.
The last rider to win atop the Alpe on the Tour was Armstrong, in 2004 when the American left Ullrich a minute in his wake on a 15km time trial.