Former WBO welterweight champion Jeff Horn is looking for revenge.

The Australian boxer says he is more motivated than ever to face his countryman, Michael Zerafa.

Horn has exercised his immediate rematch clause, to face Zerafa for a second time - after suffering a shocking knockout loss in a middleweight clash which took place in Bendigo in August. The rematch will likely land on a date in December - with the 14th of that month being kicked around by some.

Zerafa’s trainer Sam Labruna is furious with Horn's decision.

Apparently Zerafa was in like for a very lucrative opportunity against WBA "regular" middleweight champion Ryota Murata

With Horn exercising that clause, it means Zerafa will miss out on a pile of money with Murata.

"We meet with Team Horn and plead with him to let Michael Zerafa take this money and opportunity so Michael can get a deposit for a home," Labruna posted on Facebook.

"Jeff Horn comes back and denies Michael Zerafa the opportunity and enforces a re-match - how very un-Australian is that?"

Horn claims that he was offered a lot of money for different fights in the United States, but wanted revenge.

"I did consider giving him that opportunity. He has a world title on the board and it was a hard one for me. But it was like, 'Can I get motivated to fight one of these other guys in the US?’ which they offered me to step out of the way but I just couldn’t get myself motivated to do that. I need to fight Zerafa again. I really needed to get this back and have the slate clean," Horn said to AAP.

"It does make it easier to get into the gym when they are calling me all these names. His team have had a lot to say and have been pretty harsh with their words but it was in the contract. And he is always going to get big opportunities if he beats me in the re-match - but he has got to beat the real me the second time.

"I was a little bit guilty of cutting corners the last time, nothing massive but little things that made me mentally underestimate Zerafa and he proved his point on the night so good on him. It was embarrassing [the August loss]. I definitely didn’t fight the way I normally do. But I have a hunger ... to get that win back and a world title after that would be great."