The Spanish doctor accused of masterminding a doping ring in cycling has admitted he had clients in other sports including football, tennis, athletics and boxing.
Eufemiano Fuentes is on trial in a Spanish court nearly seven years after police seized anabolic steroids, transfusion equipment and blood bags as part of an investigation dubbed Operation Puerto.
London's Daily Telegraph reporter covering the case Nick Hoult says some big names in the world of sport could potentially be brought down.
He says it would be a huge story if it was to come out that Fuentes was working with high profile footballers and tennis players.
The trial is due to end in mid March.