The eagerly-awaited showdown between under-fire Alexander Zverev and Nick Kyrgios, who blasted the German as "selfish" for partying just days after a coronavirus scare, was cancelled on Wednesday after both men withdrew from an exhibition event in Berlin.
Both men were slated to join world number three Dominic Thiem at the mens and womens tournament from July 13-19 in the German capital.
"I was planning this month to play in Berlin, but I have made the decision to stay put and train with my team and not play any tournaments at the moment," Zverev, ranked seventh, wrote on social media.
"It's never nice to miss the chance to play at home, but I will be back soon," added Zverev who said ex-pro David Ferrer has joined his coaching team on a trial basis.
Kyrgios, ranked 40th in the world, is also out amid travel concerns from Australia, where the coronavirus pandemic has worsened with Melbourne back in lockdown.
"When we got Nick Kyrgios involved in May, this development wasn't to be expected," said tournament director Edwin Weindorfer.
The Austrian added he is struggling to replace Zverev and Kyrgios, two of the biggest draws to the Berlin tournament.
"Time is extremely short, but we will do everything we can to find possible last-minute options."
News of the Berlin withdrawals comes after Kyrgios launched a controversial verbal assault on Zverev and Thiem.
Zverev, 23, was filmed partying in a busy bar despite pledging to follow self-isolating guidelines after playing in Novak Djokovic's coronavirus-hit Adria Tour in the Balkans.
Although Zverev tested negative, Djokovic, Grigor Dimitrov, Viktor Troicki and Borna Coric, who also played, were positive.
"How selfish can you be?" Kyrgios wrote on Instagram at the time in response to Zverev's party.
On Wednesday, Kyrgios accused Thiem of not being on the same "intellectual level" after the Austrian called his criticism "cheap".
He claimed it was "bad luck" that Zverev was caught partying after promising to self-isolate.
Last week Kyrgios also exchanged verbal jabs with German legend Boris Becker, who called him a "rat" for singling out Zverev.
Zverev said on Wednesday he has returned a third negative test result for COVID-19.
In the women's event in Berlin, France's Caroline Garcia has dropped out with a foot injury and will be replaced by Latvia's Anastasija Sevastova.
Alexander Zverev reached his highest world ranking of third in 2017
Australia's Nick Kyrgios is out of next week's exhibition tournanemt in Berlin