Tennis world number one Novak Djokovic has cast further doubt on whether he'll be playing at next month's US Open at Flushing Meadows. 

The Serb had recently expressed his excitement about plans being confirmed for the US Open and French Open, having previously claimed the safety conditions in New York were "extreme" and "not sustainable".

“I still haven’t decided whether I will play in the US Open, the upsurge in registered Covid-19 cases in the United States and New York in particular are not playing into the event’s hands," Djokovic told newspaper Sportski Zurnal when asked about his participation at the first Slam of the season.

He also hit out at the criticism he's received since contracting COVID-19 at his Adria Tour event last month where there were no social distancing measures in place:

“I can only see criticism lately and much of it is malicious. It’s obviously more than just criticism, it’s like an agenda and a witch-hunt are on. Someone has to take the fall, a big name."

“My intention was pure, I was whole-heartedly committed to organising a humanitarian event to help players and tennis federations in the Balkan region,” the 17-time Slam winner said. “We complied with all the laws and regulations. But we’ve learned our lessons and some things could have probably been done in a different way.”