Josh Aloiai has become the first NRL player to contract COVID-19, after his positive case prompted the cancellation of his boxing bout with Paul Gallen.
The Manly forward, who is fully vaccinated against the virus, had spent his off-season preparing for the high-profile fight in Newcastle next month.
Coronavirus also rocked the AFL on Wednesday, with high-profile Carlton chief executive Brian Cook testing positive.
Blues coach Michael Voss was identified as a close contact of Cook, meaning he was forced to isolate instead of attending the AFL Draft.
Aloiai became unwell earlier in the week, before tests confirmed he had caught the virus.
The bombshell revelation has not only forced the abandonment of Aloiai's slated heavyweight blockbuster with Paul Gallen in Newcastle next month, but also the cancellation of the entire December 9-10 double header.
The Gallen-Aloiai bout was to headline the Friday night program that also featured the much-anticipated professional debut of Tokyo Olympics bronze medallist Harry Garside.
Former NRL stars Joey Leilua and Chris Heighington and ex-world-title contender Andrew Moloney were also due to feature on the bumper schedule.
"All patrons who purchased a ticket for the event will receive a refund through Ticketek," No Limit Boxing promoters said in a statement.
"No Limit Boxing is working on an alternate card that will feature some of the biggest names in Australian boxing, including Andrew Moloney and Harry Garside."
Manly have also since confirmed Aloiai had not been in contact with any club mates, with the 26-year-old not due to return to the Sea Eagles' Narrabeen base until next month.
The case highlights the NRL's current vaccination battles.
While Manly's entire squad is believed to have had at least their first vaccination against the virus, just under 15 across the NRL are yet to have their first dose.
The NRL remain hopeful that number will be down to around five by next March come kick off, with unvaccinated players unable to play in Queensland, Victoria or New Zealand.
Clubs are continuing to weigh up how to treat unvaccinated players, with Canterbury having sent John Asiata a termination letter if he does not receive the jab.
Penrith coach Ivan Cleary meanwhile said he would not pressure Apisai Koroisau into the vaccine, after he missed out on the Panthers' premiership parade on Saturday while unprotected.
As well as Cook joining Essendon's Xavier Campbell as an AFL chief executive to record a positive test, a third player case was also confirmed.
GWS said an unnamed men's player had contracted the virus, following on from Hawthorn's Finn Maginness two weeks ago and then-Essendon player Conor McKenna last year.
The Giants said the case was not related to one in their AFLW program which was confirmed on Tuesday, with a handful of cases also confirmed across the women's league.
Meanwhile New Zealand government's decision to close its border to non-citizens until April 30 also wreaks havoc for trans-Tasman sport.
Australia have a T20 men's tour there in March with the best-case scenario the three matches will be allowed to go ahead under quarantine over the space of four days.
Teams for the 50-over women's World Cup will all have to endure two weeks' quarantine under the restrictions.
The Super Rugby Pacific fixture will need a complete overhaul as will the NBL's plans to take the New Zealand Breakers back to Auckland.
Wellington Phoenix also face the prospect of another all-away A-League campaign, with their women's team staring at the possibility of an inaugural season spent entirely in Australia.
Australian Associated Press