Lance Armstrong's former doctor Michele Ferrari says the disgraced American cyclist could have been just as successful without doping.
Armstrong said in last week's interview with Oprah Winfrey that winning seven Tour de France titles would have been impossible without banned drugs.
However, on Ferrari's website, the Italian doctor wrote "I think Lance is wrong."
Ferrari describes the effects of testosterone, EPO and blood transfusions, and says that had Armstrong taken testosterone in the manner and amount described by his former teammates, it would have simply had a "placebo effect."
He adds "Armstrong would have achieved the same level of performance without resorting to doping, also thanks to his talent which was far superior to the rivals of his era."
Ferrari has been banned for life from the sport.