NBA superstar Giannis Antetokounmpo and his brother Thanasis wished Kambosos success in a video posted to his Instagram story on Thursday.
'Good luck during the fight,' Thanasis says. 'We will be watching. You make us all proud.'
Giannis adds, 'Let's go hard!'
Giannis and Thansis were born and raised in Greece, and are patriotic Greeks who play for their country's national team.
Kambosos' grandparents came to Australia from Greece and he has close ties to his ancestral home, sports tattoos of the Greek flag and Spartan warriors, and said of his upcoming fight, 'June 5th is not only for myself but for my country - Australia and Greece.
We will continue to shine on the world stage and be victorious.'
The lightweight world champ replied to the brothers' post by writing, 'Thanks @Giannis_An34 and @Thanasis_ante43 for the message of support leading into the super fight .. We will continue to bring honour and pride,' accompanied by a Greek flag emoji.
This will be the biggest boxing contest of the year and will bring thousands of fans to Melbourne to see this match.