Djokovic frustrated players in the dark over doping cases

"I'm just questioning the way the system works, really, and why certain players are not treated the same as other players."

Serbia's Novak Djokovic attends a training session before the Brisbane International tennis tournament in Brisbane  (Photo by PATRICK HAMILTON/AFP via Getty Images)

Novak Djokovic expressed his frustration at being "kept in the dark" about world number one Jannik Sinner's doping case, saying in Brisbane on Sunday that it was not a good look for tennis.

Anti-doping authorities said in August Sinner twice tested positive in March for the anabolic androgenic steroid clostebol and was cleared of wrongdoing by an independent tribunal that accepted his explanation of unintentional contamination.