It wasn't exactly the kind of rest day questioning Michael Rasmussen would have expected a day after riding into the yellow jersey for the first time of his career.

The Tour de France leader patiently defended himself Monday against tough questioning from journalists who queried him about rumors he was one of the UCI's infamous "Men in Black."

"It's strange that the UCI says I am training in neutral colors. The only ‘Men in Black' I know of are Will Smith and Tommy Lee Jones," Rasmussen said in a rest day press conference. "It's true I sometimes train in neutral colors to respect my privacy. When I ride in my Rabobank jersey, people follow me home, they hang out of cars, stop me and ask for autographs. I don't like that. That why I sometimes train in neutral colors."

UCI anti-doping coordinator Anne Gripper raised doubts about several riders she dubbed as "Men in Black" who she insinuated raced in non-team jerseys ahead of the Tour to allegedly try to avoid detecting from pre-race doping controls.

Rasmussen roared into the yellow jersey in a dramatic display Sunday that have many wondering if the climbing specialist can hang on to win the Tour.

But journalists seemed more interested in asking him about rumors of training practices, particularly his penchant to go to far-away Mexico for high-altitude training camps. Rasmussen's wife is Mexican, but some suggest riders go to Mexico because the Latin American nation would seem a safe haven for dubious training practices.

"I've been using high-altitude training methods since we went to Colorado in 1994 with the Danish national mountain bike team," the former world mountain bike champion said. "After that experience, I've always believed in high-altitude training."

Rasmussen didn't flinch when one Danish journalist asked him point blank if fans should trust him following the damaging revelations from 1996 Tour champ Bjarne Riis.

"Yes, you can believe me," Rasmussen answered. "Unfortunately, this is what we have to deal with now in cycling. Fans can believe me."