The positive drugs test by the three-time Tour de France winner, Alberto Contador, has thrown up more questions about drugs in the sport.
The Spanish star has been provisionally suspended after testing positive for a miniscule concentration of clenbuterol during this year's Tour, but he claims his failed test resulted from eating contaminated meat on the second rest day of the tour in July.
Contador would have been tested every day of the Tour, but this positive test only showed up once.
The cycling journalist Alister Fothringham, who is based in Spain and who attended Contador's media conference, says if the authorities accept his story it will have a big impact on the sport.
Fothringham says the case could cause the interntaional cycling body, the UCI, and the anti-doping authorities to re-look at testing procedures.