Novak Djokovic has weighed in on tennis's high-profile doping cases and criticized what he perceives as double standards in the sport.

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Novak Djokovic says Nick Kyrgios has 'spoken well' about Jannik Sinner 's doping case after the Aussie labelled the scandal 'disgusting' for tennis.

Novak Djokovic told reporters in Australia that he "is not questioning whether Jannik Sinner took the banned substance intentionally or not" but noted that he is "really frustrated" with the fact that no one knew anything about the Italian and Iga Swiatek until the investigation in their doping cases concluded.