The International Cycling Union has raised doubts over whether Lance Armstrong will be legally allowed to compete at January's Tour Down Under in Australia.
The seven-time Tour de France winner has targeted the first Pro Tour race of the season as his comeback race after a three-year absence from the road peloton.
But the UCI, world cycling's ruling body, says Armstrong will have to show he has respected UCI's 'biological passport' rule demanding that athletes must be registered with an anti-doping programme six months prior to competing.
UCI chief Pat McQuaid says he doesn't know what date Armstrong asked to be registered on the programme but the UCI will apply the rules regardless of the athlete.
