The enforced absence of Alberto Contador from this year's Tour de France as he serves his suspension for doping has left the event appearing wide open for who will challenge for the yellow jersey.
Leading the field, Cadel Evans, the Australian veteran, will defend his title, and Olympic champion Bradley Wiggins hopes to give Britain a first victory at cycling's biggest event, just days before the London Games.
The 99th Tour starts today in Liege, Belgium, and will cover 3,500 kilometres over three weeks.
Race planners have given slightly more weight this year to time trials compared to mountains, generally seen as the twin pillars in cycling races that separate title hopefuls from the stragglers.
The Olympics, which start less than a week after the Tour ends, is casting a shadow on this year's race, and has forced some riders to choose one event or the other.
Belgian sprinter Tom Boonen and promising American Taylor Phinney are skipping the Tour to focus on the London Games. American Tyler Farrar - who plans to ride in both - has said it's "a little frustrating" that cycling has two of its biggest events nearly back-to-back.
Once again, cycling's longtime doping scourge looms large. Contador, the biggest name in cycling since the Lance Armstrong era, had one of his three Tour titles stripped in February and was banned from racing to August after he tested positive for the banned stimulant clenbuterol in the 2010 Tour.
Pre-race injuries and illness also have depleted the cast of contenders. RadioShack Nissan leader Andy Schleck of Luxembourg, who inherited Contador's 2010 title and is also a two-time Tour runner-up, will be at home after injuring his spine this month in the Criterium du Dauphine race. Norway's Thor Hushovd, who won two Tour stages last year, is out while he recovers from a virus.
At least one Tour record will be rewritten this year. American veteran George Hincapie, a BMC teammate of Evans and Armstrong's longtime lieutenant during his run of seven Tour titles, will begin his 17th Tour de France - breaking the record he had shared with Dutch legend Joop Zoetemelk for the most Tour starts in history.
This race also looks like one of the most promising in years for Britain, in particular through Team Sky. Mark Cavendish, one of the world's top sprinters who already has 20 Tour stage victories, recently joined the team.
But he has said he expects to be less dominant in Tour sprints this year because he has changed his training and lost weight with an eye to the Olympics.
He also will be without his longtime lead-out man, Mark Renshaw of Australia, who is on Dutch squad Rabobank.
Plus, Sky has put the lion's share of its resources behind Wiggins, who crashed out of last year's Tour and wants to give Britain at least its first podium finisher at the Tour - if not an outright winner.
This season, the three-time Olympic track champion has again proved his success at morphing into a road racer, winning three competitions, including this month's Dauphine Libere.
Evans, who was third in that race, remains a question mark: The 35 year old did not race in May and this year has won only the three-day Criterium International in April.
The BMC team leader still has a strong cast of supporters including Hincapie, Philippe Gilbert of Belgium, and young American rider Tejay Van Garderen.
This year's race features three uphill finishes, which is relatively few by recent Tour standards. The first comes on the eastern Vosges range in Stage 7, with a short, steep ride up the Planche de Belles Filles - a plateau named for a legendary mass suicide of French damsels faced by the threat of Nordic invaders centuries ago.
The others are rides up to ski stations: La Toussuire in the Alps in Stage 11, and Peyragudes in the Pyrenees in Stage 17.
In keeping with tradition, the course in this even-numbered year runs clockwise around France.
After three days in Belgium, the race cuts from the English Channel across northern France to the Vosges, down to the Alps, down to the town of Cap d'Agde on the Mediterranean Sea, then into the Pyrenees, followed by a dash up to Paris for the July 22 finish on the Champs-Elysees.
This year, more than most, time trials will get star billing. The race against the clock, in which riders set off one by one, is a discipline traditionally dominated by riders like Wiggins, Switzerland's Fabien Cancellara of RadioShack Nissan - a favourite for today's 6.4-kilometre prologue in Liege - and Germany's Tony Martin of Omega Pharma-Quick Step.
Outside threats for overall victory include Dutch rider Robert Gesink, the winner of the Tour of California this year, American veteran Levi Leipheimer - generally solid in both time trials and the mountains - and Italy's Vincenzo Nibali.
The International Cycling Union promises hundreds of anti-doping tests during the race, on par with last year, as part of the continued effort to root out drugs cheats.
The doping cloud in cycling re-emerged this month when the US Anti-Doping Agency filed formal doping charges against Armstrong, threatening to strip him of his seven Tour victories.
The agency also brought charges against Armstrong's longtime manager Johan Bruyneel - the current manager of the RadioShack Nissan team - and four others linked to the American's former teams. Armstrong has forcefully denied the allegations.