Alberto Contador is looking to confirm his billing as the Tour de France favourite and regain the title he claimed in 2007.

Armstrong's return after an absence of over three years left Contador's position as Astana's leading rider in jeopardy, but, if there was a power struggle with the American, it is the 26-year-old who came out on top.

"It's hard to find a better stage race rider than Alberto," said Astana general manager Johan Bruyneel, who oversaw all of Armstrong's seven triumphs and Contador's win two years ago.

"He has worked very hard, earning the right to represent the team as leader."

In 2008, Contador moved to Astana from the Discovery Channel team, but missed his defence of the title due to a ban imposed on the Kazakh-backed squad by Tour de France organisers Amaury Sports Organisation for a doping-riddled campaign under the previous regime.

However, the Spaniard put that disappointment behind him and triumphed in the Giro d'Italia and the Vuelta a Espana, becoming the fifth cyclist in history to win all three Grand Tours.

That is something Armstrong has never achieved.

The American focused his full attention on the month of July before retiring after his seventh successive triumph in 2005.

In May, however, the 37-year-old competed at the Giro d'Italia for the first time, finishing a respectable 12th, and appearing to become stronger in the final week, despite breaking his collarbone at the Vuelta a Castilla y Leon in Spain little more than a month before the start in Venice.

Armstrong will now support Contador in the 21-stage, 3,500-kilometre race through six countries, which begins in Monaco tomorrow and ends in Paris on July 26.

Contador fine-tuned his build-up with victory in the Spanish time-trial championships last week after a third-placed finish in the Dauphine Libere - his first race since April - and is the top pick of many of cycling's luminaries.

"Contador is the favourite, certainly," Sean Kelly, who won the points jersey at four Tours de France, told Press Association Sport.

"Before Dauphine he would have been the favourite, but in the Dauphine Libere he was a little bit under what we would normally see in that kind of very mountainous race, where he would usually be very, very dominant.

"The question is, did he take a bit of a break before Dauphine and not come in at 100%? That is quite possible.

"Was that the plan, to be at 80-85% and use Dauphine as a stepping stone to the Tour de France? To come into the Tour de France at 100%?"

David Millar, who will begin his eighth Tour de France tomorrow, agreed with Kelly's assessment.

He told Press Association Sport: "The man to beat is Contador, there's no doubt about that."

The route of the 96th Tour includes seven mountain stages and three summit finishes, one of which involves climbing the demanding Mont Ventoux in a penultimate stage Kelly believes could be decisive.

"If there's somebody in the lead who has shown a little weakness in the last number of days then it will be a major nightmare for that person who will be in yellow going into that penultimate day," said Kelly, who will be commentating on the race for British Eurosport.

Kelly believes Contador's main challengers are Evans, the runner-up in the last two Tours, and defending champion Carlos Sastre.

He would also not bet against Armstrong, who returned to the sport to publicise the campaign against cancer, making an impact.

However, Armstrong's enduring unpopularity in France - many French cycling fans believe the cancer survivor doped his way to glory, despite the fact he has never failed a drug test - could continue.

Inevitably, the subject of doping and cheating is sure to crop up and punctuate the Tour.

Millar, who served a two-year ban for EPO, is well qualified to discuss the subject.

Now a member of the World Anti-Doping Agency's athletes' committee, he added: "There are always going to be guys that do it to some degree, it's human nature.

"But what we're trying to do is change it so it's not across the board and everybody has a fair chance."