The man tasked with eliminating drug cheats has expressed the belief that criminal gangs now control a quarter of all world professional sport.
David Howman, director general of the World Anti-Doping Agency, called for everyone involved in the fight against corruption in sport to band together to ensure the "bad guys" don't win.
"The biggest threat to sport is organised crime," Howman told delegates in London for a conference on sport security.
"Don't let us compartmentalise it into match-fixing or bribery, it's organised crime.
"And I think, now, organised crime controls at least 25% of world sport in one way or another."
Howman said those who were distributing drugs are the same characters who corrupt athletes and pay money to fix games.
"They're the same bad guys," he told delegates.
"Now, the good guys have to prevail. Who are the good guys? Let's get them together and make sure they can work out a plan.
"Because, otherwise, the bad guys are going to win."
