(USA TODAY) - Floyd Mayweather labelled Conor McGregor a “dirty” fighter on Thursday, and admitted he fears the Irish mixed martial arts star will use roughhouse tactics during their boxing match on Aug. 26.

Mayweather admitted he had seen clips of McGregor in training and insisted that many of his moves and tactics stretched the bounds of boxing’s strict regulations.

“I see a lot of rabbit punches behind the head, grappling, wrestling, illegal shots,” Mayweather said on a media conference call. “But the ref will be fair on both sides, I want him to be even. I want us to have a good solid fight.”

McGregor has stipulations in his contract that would impose a severe financial penalty if he was to employ the kind of moves he typically uses in the Ultimate Fighting Championship, such as kicks and elbows.

However, “dirty” boxing moves do not fall under that category, and would need to be controlled by referee Robert Byrd in the ring. It should also be noted that Mayweather has been accused of using elbows himself, especially by former opponent Victor Ortiz.

McGregor hired retired official Joe Cortez to look over his sparring sessions in training, in order to ensure he remains within the rules.

“I truly believe (Byrd) is going to do his job, his job is to keep the bout clean,” Mayweather added. “We are going to have a hell of a fight. Like I have said, I am coming straight ahead.

“I look forward to following the Queensberry rules of boxing. (McGregor) had Joe Cortez in his training camp but I still see him being extremely dirty. But my job is not to referee the fight, I am going to do my job. I am not worried about the outcome, I am more worried about excitement.”

Despite teasing in various television interviews that he may be prepared to fight McGregor a second time, perhaps even in a mixed martial arts octagon, Mayweather was adamant on Thursday that this bout will be his last. His most recent contest was against Andre Berto in 2015, which ended in a unanimous points victory.

“I thought Berto was going to be last weigh-in, last training camp, my last everything,” Mayweather added. “But you just never know what can happen and we are here with this big event. This is my last one, ladies and gentlemen. I gave my word to (advisor) Al Haymon, my children, and I don’t want to break that. I want to stick to my word. This will be my last fight.”