Surreal scene Down Under ... tennis fans PACKED a stadium to watch tune-up games for the Australian Open -- with masks nowhere to be found!!!
... and Serena Williams loved every second of it!!!
Don't worry -- this wasn't a super-spreader event ... because of strict quarantine rules and other regulations in place to fight COVID, Australia is actually a coronavirus-free area.
In fact, officials announced Friday the entire country hasn't had a positive case in nearly two weeks!!!
So, an estimated crowd of around 4,000 jammed into an arena in Adelaide on Friday to watch tennis stars like Serena Williams, Naomi Osaka and Novak Djokovic prep for the Aussie Open .