A Spanish doctor who may hold the secrets to drug cheating in football and tennis, has gone on trial in Madrid.
The public health charges against Eufemiano Fuentes relate only to cyclists he worked with.
But the man leading the worldwide fight against doping told ITV News that the doctor was involved with athletes from a variety of other sports. ITV News Sports Editor Steve Scott reports:
The hearing to open the cycling doping trial of Spanish doctor Eufemiano Fuentes has closed for the day.
Dr Fuentes is scheduled to speak tomorrow in Madrid, Spanish media has reported, as he begins his defence against charges that he broke public health laws by conducting performance-enhancing blood transfusions.
Former cycling doper turned whistleblower Tyler Hamilton described Dr Eufemiano Fuentes as a "one-man Wal-Mart of doping" in his 2012 book The Secret Race, which detailed the use of performance-enhancing drugs in the sport.
Hamilton was among 11 former teammates who testified against Lance Armstrong during the US Anti-Doping Agency's investigation.
In his only UK interview, he gave ITV News his reaction to Armstrong finally confessing.
Tour de France stars Alberto Contador, Alejandro Valverde and Ivan Basso are among the 58 former clients of Dr Eufemiano Fuentes listed in the investigation into the 'Operation Puerto' doping scandal.
Valverde and Basso are among six riders to have suffered sporting sanctions in relation to the investigation. Contador, who served a separate two-year ban for a positive test of a banned substance, has been cleared of any involvement in the Operation Puerto case.
Dr Fuentes, 57, is expected to deny that any alleged performance-enhancing blood transfusions that took place put the riders' health at risk. Four others, including Fuentes' sister Yolanda, will also answer the charges.
Dr Eufemiano Fuentes, who stands accused of masterminding one of sport's largest doping rings, faced intense media interest as he arrived at a court in Madrid this morning ahead of his trial.
Hearings have begun this morning in the trial of Spanish doctor Dr Eufemiano Fuentes, who stands accused of masterminding one of sport's largest doping rings.
Dr Fuentes, who arrived amid a media scrum at the Madrid court, is accused of doctoring the blood of more than 50 professional cyclists. He is charged with breaking public health laws as Spain lacked anti-doping laws at the time of the 2006 raid on his laboratories.
Former Tour de France champion Alberto Contador is among the many cyclists expected to testify as witnesses in the trial, which is expected to run for two months.
The World Anti-Doping Agency's initial claim that Dr Fuentes may have also doped athletes from other sports - including football and tennis - will not be scrutinised due to an apparent lack of evidence.