George Kambsos Jr calls Devin Haney as 'fake as his belt' at press conference
The Australian is making the first defence of his WBA, IBF and WBO titles against WBC champion Devin Haney.
If the opening press conference was a boxing round then Kambosos Jr would have won it 10-8.
The unified lightweight champion turned the heat up ahead of his fight against Haney this weekend in Melbourne.
The winner will become just the eighth fighter to become undisputed champion since four belts were introduced and Kambosos Jr started the mind games by accusing his American opponent of being a 'sneaky informant'.
"I really don't know how they let this guy into the country, to be honest. I don't think they let informants into the country," said Kambosos Jr.
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"This guy is an informant, this guy is a rat. I will tell you why. In the Teofimo Lopez fight, he was messaging me, telling me all the details, every bit. 'Teo at the hookah lounge, Teo having problems with his wife.'
"This is the kind of person? This is a rat. This is a sneaky informant, and you know what? Your own countryman, you're going behind his back. I'm gonna whip your ass, and when you get back to Las Vegas, you'll be on the lookout for Teofimo Lopez, because he'll be looking for you, too. Trust me.
"This guy acts like a gangsta, he ain't a gangsta, he's as fake as that belt."
"It's OK, I've been the underdog my whole career," added Kambosos when asked about his thoughts on being the outsider.
"I was never meant to be here. I kept turning up and I am the top dog, I am the top guy. It's no problem. He can have me whatever odds, just like I was in the Lopez fight, and I will handle business."