Travis Tygart, the head of the US Anti-Doping Agency (USADA), and the man who was instrumental in revealing Lance Armstrong's doping practices, has spoken out against International Olympic Committee president Thomas Bach's claim that "doping will always happen".
In an interview with CNN Money Switzerland on August 21, Bach told interviewer Martina Fuchs: "Doping will always happen. This is one of the wars you cannot win."
When asked whether that meant that stricter anti-doping measures needed to be adopted, Bach replied: "This is up to the World Anti-Doping Agency [WADA]. The IOC has only the responsibility to have the doping tests and the sanctions on the occasion of the Olympic Games."
On Tuesday, Tygart told CNN World Sport in response to Bach's comments that giving in was like sprinting superstar and eight-time Olympic gold medallist Usain Bolt or 23-time Olympic swimming champion Michael Phelps giving in.
"It's obviously a tough fight, but the leader of sport, or anti-doping, can't simply throw in the towel," said Tygart.
"I mean, can you imagine if Michael Phelps or Usain Bolt walked into an Olympic final and said, 'I can't win this'?
"It's not the focus, it's not the determination, it's not the commitment that clean athletes expect and deserve."
Asked why he thought Bach had said what he did, Tygart said that he didn't know.
"I don't know if it's excuses for the failure to take meaningful consequences against Russia's state-supported doping, or if it's a prediction of the future."
Tygart has also butted heads with WADA in recent months.
He told BBC Sport in late July that WADA's closure of the Chris Froome salbutamol case ahead of this year's Tour de France was "another blow to the perceived credibility of the global anti-doping movement".