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.

Just a week before the start of the US Open, the ITIA announced that the top-ranked ATP player twice tested positive for clostebol in March.

However, Sinner didn’t get a day of suspension after his explanation was accepted and the ruling stated that he wasn’t to blame for what happened.

Then in late November – after the WTA Finals and Billie Jean King Cup Finals – the ITIA revealed that Swiatek’s sample from August came back as positive for trimetazidine and that she was provisionally suspended for 22 days after the US Open.

Unlike the Italian tennis star, the Pole did get a symbolic one-month ban – which expired during the offseason.

“I’ve been really frustrated … to see we’ve been kept in the dark for at least five months (on the Jannik case),” the record 24-time Grand Slam champion said at the Brisbane International.

“The ATP hasn’t really talked in depth about it. Why have they kept that case away from the public?

“We see Simona Halep’s case on the WTA Tour, now Iga’s case. It’s not a good image for our sport.

“I’m just questioning the way the system works and why certain players aren’t treated the same as others. Maybe some ranking reasons are behind it or some players have more financial backing and stronger legal teams to tackle these cases.”

The ITIA faced a certain backlash over their handling of the Sinner and Swiatek cases and some went as far as to claim that double standards were involved.

But Djokovic is by far the biggest name to publicly call for some answers regarding these doping cases.