Contador wary of Armstrong's threat

Armstrong, 38, announced via social networking website Twitter earlier this week that the 97th Tour de France will be his last.

The favourite for the race the American dominated from 1999 to 2005 and returned to in 2009 is Spain's Alberto Contador.

Contador believes Armstrong is capable of winning an eighth Tour and derailing his own bid for a third yellow jersey in four years.

Asked whether Armstrong can win, Contador said: "Absolutely and on his own merit.

"Last year, he got third place and this year he is riding at a very good level before the Tour. He will be fighting for victory."

Contador and Armstrong were team-mates 12 months ago.

They endured a fractious relationship and the Texan took the majority of the Spaniard's Astana colleagues with him when he established Team RadioShack, who, like BMC Racing and British squad Team Sky, will be making their Tour debut.

As they now ride for different teams, the Armstrong-Contador relationship will likely be explored less over the 3,642km of riding through Holland, Belgium and France, although their rivalry could be just as compelling.

Contador, 27, who is fuelled by British nutrition company Science in Sport, added: "Victory is the aim for which I'm training but I know everyone is waiting to see if you fail and they will look to exploit any sign of weakness."

Contador will be expected to perform well in today's 8.9km prologue in Rotterdam, but he could endure a trying time from tomorrow's first road stage until the race hits the mountains.

It is likely Contador's rivals – including Armstrong, world road race champion Cadel Evans (BMC Racing Team), 2009 runner-up Andy Schleck (Team Saxo Bank) and Bradley Wiggins (Team Sky) – will attempt to unsettle the Spaniard in the early stages, where cross-winds and cobbled sections could have a significant impact.