Former cycling world champion Tom Boonen has won his battle to race in the Tour de France despite testing positive for cocaine.

Just 24 hours before this year's race starts in Monaco, the French Court of Arbitration for Sport has backed Boonen's appeal.

Race organisers banned the Belgian for failing an out-of-competition test for cocaine in April. It was the 28-year-old's second offence in 12 months after he tested positive for the same substance last year.

However, the 2005 world champion launched his appeal as a positive test for cocaine out of competition is not an automatic ban under World Anti-Doping Agency rules.

Boonen's Quick Step team welcomed the ruling, but regretted that a decision took so long. "I'm relieved but I'm sorry that we had to go up to here," said team manager Patrick Lefevere.

"The pressure has been huge, not only on Tom Boonen's shoulders but on the whole team."

Briton Mark Cavendish, who finds himself with a new rival for the best sprinter's green jersey, welcomed Boonen's entry into the three-week race.

"It changes many things and in a good way. Our team will have less pressure in the flat stages," Cavendish said.

The race, which begins with a 15.5km time trial on the streets of Monaco tomorrow, sees the return of seven-time champion Lance Armstrong.

Britain's Bradley Wiggins is among those who believes the American could become the oldest winner in Tour history at the age of 37.

"It'll be damn hard for him but you wouldn't write the guy off," he said. "People have done that in the past and he's proved them wrong every time."

Stage one: Tomorrow - Monaco, 15.5km. First rider starts at 3pm. Last rider 6.30pm. TV coverage on ITV4 and British Eurosport.