On Monday in Australia, lightweight champions George Kambosos and Devin Haney came face to face for the first time during a press conference event to further hype for their upcoming showdown.

They are set to collide on June 5 at Marvel Stadium in Melbourne (June 4 in the United States), with the WBC, WBA, IBF, WBO world titles at stake.

During the press conference, Kambosos made allegations that last year Haney messaged him several times in order to provide him with sensitive information pertaining to Teofimo Lopez’s training camp.

Kambosos shocked the sport when he dropped and outboxed Lopez last November to capture the unified lightweight crown.

"This guy is an informant. This guy is a rat. Teofimo Lopez fights against a foreigner, he was messaging me. He was telling me all the details. 'Teo at the hookah lounge, Teo having problems with his wife.' This is a rat. This is an informant," Kambosos said.

“You know what, on Sunday, I’m going to whip your ass. And you know when you get back to Las Vegas, you’re gonna have to look out for Teofimo Lopez, because he’s going to be looking for you too."

Kambosos also threatened to leak the text messages if Haney or anyone in his camp disputed the information.

The Australian boxer recently posted video footage to social media, where Haney and his father, Bill Haney, were celebrating the upset win over Lopez.

Haney believes Kambosos is presenting himself as a tough guy to put on an act for the public.

“When is the act gonna stop,” Haney said. “We can see right through it. Just be you, that’s all you gotta do. Be you. You’re acting.”

Kambosos fired back to that claim.

“I’d rather be an actor than a rat," Kambosos said.