Alexander Zverev and Nick Kyrgios were slated to join Dominic Thiem at an exhibition tournament from July 13-19 in Berlin.
Alexander Zverev was heavily criticised after viral footage emerged of him partying in a busy bar despite pledging to "follow self-isolating guidelines" after playing in Novak Djokovic's coronavirus-hit Adria Tour.
Nick Kyrgios was involved in a Twitter battle with Boris Becker after the Australian took issue with fellow-tennis player Alexander Zverev.
After testing negative for coronavirus, Alexander Zverev had released a statement vowing to self-isolate, only to be spotted at a busy bar, apparently over the weekend, in footage that went viral.
Nick Kyrgios, Dominic Thiem and Alexander Zverev have been signed up to take part in Berlin.
Novak Djokovic has been criticised for hosting the exhibition tournament that has led to a slew of players testing positive for coronavirus, including himself.
Novak Djokovic appears doomed never to be held in the same saintly esteem as Roger Federer or Rafael Nadal, the undisputed 'people's champions' of tennis.
New York Governor Andrew Cuomo gave the green light for the US Open to be held from August 31 to September 13.
Nick Kyrgios suggested it was too early for the Flushing Meadow Grand Slam, joining other players in expressing reservations, including world number one Novak Djokovic.
The ATP and WTA tours are both suspended until late July due to the global health crisis.
Andy Murray, appears to be one of his few rivals Nick Kyrgios respects, with the Scot having defeated Novak Djokovic in both the 2012 US Open and 2013 Wimbledon finals.
Last month, Dominic Thiem had expressed scepticism about plans to set up a fund to help lower-ranked players struggling because of the shutdown of the sport.
As the coronavirus has sent the tennis season into hibernation, a host of players have recently taken to social media for face-to-face exchanges.
Stefanos Tsitsipas posted a picture of himself standing outside and holding up a home-made cardboard sign with a phone number and the words "call me" scrawled on it.
WTA founder Billie Jean King and Rafael Nadal led a wave of support on Thursday for Roger Federer's suggestion that "now is the time" to merge the men's and women's governing bodies
Nick Kyrgios said he would personally drop food on doorsteps after COVID-19 restrictions closed down entire industries in Australia.
Eugenie Bouchard requested her fans to stop sending "dating resumes" following one of her tweets that read "quarantine would be a lot more fun with a boyfriend".
Nick Kyrgios is dealing with a wrist injury while Alex de Minaur continues to struggle with an abdominal tear that he picked up at the season-opening ATP Cup.