Spanish ace Carlos Sastre faces the race of his life over the next 21 days if he is to become the first rider since seven-time champion Lance Armstrong to successfully defend a Tour de France crown.
The three-week epic clicks into gear with a 15.5km time trial in Monaco on Saturday's first stage and Armstrong, despite a four-year absence from the race, is not ruling himself out of victory contention.
After completing a pre-race training camp of key stages in the Alps, the 37-year-old American who returned to competition in January said his form was similar to that of 2003 - when he beat German rival Jan Ullrich by just over one minute to win his fifth yellow jersey.
"I'm coming to the Tour with the best form possible but we'll see how it goes after the first few days," said Armstrong. "There's no way I can say I have a chance of winning, as I could in previous editions. I feel a little bit like I did in 2003, when I just beat Ullrich."
There are many uncertainties heading into the 96th edition of the world's biggest bike race, but one thing is sure: the normally discreet Sastre may have to show his face a lot more often at the front of the bunch when it matters.
Among a host of challengers will be two-time runner-up Cadel Evans of Australia, Russian Denis Menchov, the recent Giro d'Italia winner, and Luxembourger Andy Schleck, a former runner-up on the Giro.
But the quality-packed Astana team which also includes 2007 champion Alberto Contador, American Levi Leipheimer and German Andreas Klöden could be Sastre's real undoing. The Kazakh-backed outfit come to the Tour having only recently resolved financial problems, but that is unlikely to weigh too heavily as they aim to avenge not being invited to the 2008 edition by winning the race this year.
But just who will lead their charge remains to be seen.
Armstrong has described Contador as the "best stage racer in the world", praise which, given the 26-year-old Spaniard's pedigree, can certainly be justified.
A third place finish behind Evans at last month's Dauphine Libéré, a major warm-up for the Tour, showed that both Contador, and Evans, are on form.
Contador then went on to claim his first national title in the time trial on a bike he was testing ahead of the Tour.
"My preparation for the Tour is done. I can't complain. I am ready," declared Contador.
Despite Astana's strength in depth doubts remain, however, over how much support Contador will receive throughout the 3,459.5 km round trip from Monaco to Paris.
Astana's team manager is Johan Bruyneel, who helped orchestrate Armstrong's seven Tour wins and Contador's victory in 2007. Last week the Belgian named Contador as team leader, but had a special mention for his old friend Lance.
"After three plus years away from competition I'm very happy with where Lance's form is leading up to the Tour," Bruyneel purred. "He's worked very hard during his comeback season and I know he is extremely motivated for the Tour de France."
On the race itself, the hostilities between Sastre, Contador, Menchov, Schleck and Evans should kick off over three days in the Pyrenees mountains, starting on stage seven.
A strong climber who has worked hard to improve his time trialling, Sastre is never happier when he is forgotten about - although that wish is unlikely to be fulfilled this year.
"Let people talk about the others and let them forget all about me, that's all I ask," said the Spaniard, who won two stages at the recent Giro d'Italia where he finished fourth overall.
"The only thing that matters is your place in the general classification when the race finishes on the Champs-Elysees."
After the Pyrenees the yellow jersey battle is likely to re-ignite over the remaining five days of climbing, and the two individual time trials.
Beginning with a medium-mountain stage near Colmar in eastern France, the race rides over the Swiss Alps, through Italy and then takes in two tough days of climbing in the French Alps prior to the big finale.
In keeping with their bid to maintain suspense right till the end, organisers have this year done away with the traditional penultimate stage time trial and replaced it with the monster climb to the Mont Ventoux.
It is where British legend Tommy Simpson died in 1967, and where the likes of Eddy Merckx, Armstrong and a few other big Tour names have helped forge their yellow jersey triumphs.
Despite the peloton's hard-fought endeavours over the previous 19 stages of the race, the yellow jersey this year could be decided on the gruelling 21.1 km climb, at an average gradient of 7.6 percent, to the summit of the ominously named 'bald mountain'.