(CNN) -- World Anti-Doping Agency (WADA) president John Fahey has told CNN he doesn't think Novak Djokovic "has the faintest idea" what his organization does after the former world No. 1 said he'd lost faith in the system. The Serbian labeled compatriot Viktor Troicki's 12-month ban from tennis for missing a drugs test a "total injustice" and said he was now nervous to give any sort of sample. But Fahey dismissed the six-time grand slam winner's comments as unhelpful and said it was up to the sport to do more to fight against doping. "I don't think Novak Djokovic has the faintest idea what we do and if he wants to understand what we do I'm more than happy to pick up the phone and talk to him, if he wants to talk to me," he told CNN.
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WADA president John Fahey replies to Novak Djokovic's criticism
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World No. 2 tennis star said he'd lost faith in agency after Viktor Troicki's ban
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Fahey tells CNN that Djokovic "hasn't got the faintest idea what we do"
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He says Lance Armstrong case shows that no-one is above the regulations
But Fahey thinks @placeholder's descent has proved that drug cheats will be caught out and punished no matter what their status.