Promoters of the April 22nd Jeff Horn vs. Tim Tszyu fight have postponed the event, hours after communicating it was going ahead as scheduled.
The U-turn comes as the coronavirus pandemic grips the world and just two days after Australian Prime Minister Scott Morrison banned mass gathering of 500 or more people in a bid to slow down the spread of the disease.
It is unclear at this stage when the 'Rumble on the Reef' bout will be rescheduled, but it is expected to remain at the Queensland Country Bank Stadium in Townsville.
The super welterweight fight was to be over 10 rounds with the winner likely to earn a world title shot later in the year.
The Horn-Tszyu mega fight is the latest Australian sporting event to be impacted by the coronavirus.
Last week, Formula One's season-opening Australian Grand Prix was called off after a McLaren team member contracted the virus. The AFL, NRL, NBL and Super Rugby competitions have also been impacted.