Contador clearly showed his American teammate and rival he deserved to be the leader of their Astana team with a rock-solid performance in the opening time-trial Saturday in the hilly streets of Monaco.

Contador, who won the Tour in 2007, finished second in the demanding 15.5-kilometer (9.6-mile), 18 seconds behind stage winner Fabian Cancellara of Switzerland.

More importantly, in his bid to win the cycling's most prestigious race again, the 26-year-old, whose legs are 11 years fresher than Armstrong's, took a 22 second advantage over the man who ruled the Tour seven years in a row.

"I'm not interested in whether I'm the leader or not, the important thing is that it's a big boost to my morale, and it shows that I'm in a good form," Contador said. "Those seconds are welcome because the Tour is going to be very tight."

Armstrong, back on the Tour four years after his last victory in 2005, displayed a strong performance and finished 10th, 40 seconds behind Cancellara.

For the American, it was like the good old days around his team bus, with dozens of cameramen surrounding him and fans of different nationalities screaming his name. The melee annoyed some other riders who struggled to find a path to the start ramp.

"There is not only Armstrong in life!" said Frenchman Stephane Auge on his way to the line.

But on the road, Armstrong, who posted his worst result in a time-trial since his first Tour win in 1999, was not "Le Boss" anymore. The American appeared less powerful on the saddle than during his dominant years and was somewhat cautious in the long descent punctuated by some dangerous hairpin turns.

"I didn't expect to win or to take the (yellow) jersey," Armstrong said. "I didn't expect a super, super performance. I was nervous, which is logical with the years away. I didn't feel necessarily comfortable."

Contador's performance takes on more importance when you look at the riders in the top 10 of the stage. The Spaniard was able to beat by one second third-place finisher Bradley Wiggins, who won gold at the Beijing Olympics in individual pursuit, and he took a psychological ascent on all his main rivals. Two-time Tour runner-up Cadel Evans of Australia was fifth, 23 seconds behind Cancellara; Giro d'Italia winner Denis Menchov trailed 1:31 back, in 53rd place and Carlos Sastre, the reigning Tour champion, was 1:06 behind Cancellara.

"I expected Alberto to be the best of the team, this was an ideal course for him," Astana manager Johan Bruyneel said. "He did a beautiful time-trial."

One of the five riders to have won the three big Tours (France, Italy, Spain), Contador is returning to the French race for the first time since his 2007 victory. He didn't race last year because the Astana team was banned for past doping incidents.

Considered the best climber in the world, he improved his speed a lot this year and captured the Spanish national time-trial title last month.

"I am very happy about this result," Contador said. "My form is good, I must try to keep up this level. I've started well. I would really like to have the yellow jersey."

Contador can in theory count on the best team of the field, which placed four riders in the stage's Top 10: behind Contador, Andreas Kloden of Germany was fourth and American Levi Leipheimer was sixth in front of 10th-place finisher Armstrong.

"Now that Contador is in front, all the others in the team should work for him," said former five-time Tour winner Bernard Hinault.

"Contador clarified the situation. I don't think Armstrong can still consider himself as a leader. The team has a rider in front, if they race against each other they risk losing everything."

Contador now seems poised to grab the yellow jersey next Tuesday in Montpellier, where a 39-kilometer (24.23-mile) team time-trial is planned.

"Cancellara's Saxo Bank have a good team and it's an 18-second gap, it's a pretty big difference," Bruyneel said. "Maybe it's possible, but it's not an objective."

Cancellara, of the Saxo Bank team, will wear the overall race leader's yellow jersey for Sunday's second stage _ a 187-kilometer (16.2-mile) ride across plains from Monaco to Brignoles, France.