Gennady Golovkin claims Canelo Alvarez is one of the dirtiest fighters he has ever faced

Undefeated GGG, 36, takes on his middleweight rival in Las Vegas on September 15 after a controversial draw in their first outing.

The fight was postponed in May after Alvarez, 28, tested positive for banned substance Clenbuterol while in training camp.

And Golovkin roared: "He is one of the dirtiest and most unpleasant fighters.

"He's a dirty fighter for using substances and blaming others for it, it's a dirty tactic.

"We have two different styles of boxing, probably he thinks that his style is boxing, but my style is completely different.

"I hope he comes out with a fighting style that allows us to finish the contest in less time.

"He is the one who has to change everything. I do not think about what he is going to do, I think about what I need to do."

Golovkin and Canelo fought last September and could not be separated by the judges.

And after both greats claimed they had done enough to win, fans are desperate to see them collide again in one of the sport's biggest grudges.