Ammon News - "You can either be aggressive, corner [him], throw everything at it. Or take your time, be clever, then knock [him] out," says Anthony Joshua who will fight Oleksandr Usyk on September 25, live on Sky Sports Box Officeز

Anthony Joshua is "sharpening the mind" to avoid "mentally fatiguing" when he is faced by the unique movement of Oleksandr Usyk.

Joshua's IBF, WBA and WBO heavyweight championships are on the line against Usyk on September 25, live on Sky Sports Box Office, from the Tottenham Hotspur Stadium in London.

Joshua exclusively explained to Sky Sports why Usyk's footwork makes him his trickiest ever opponent: "100 per cent, he will be. Movement means you are never stationery to get hit. Movement is important.

"Concentration - when you want to [punch], you lock in, then make a move. You have to make sure your brain works.

"That can be mentally fatiguing so I am sharpening the mind so that I can concentrate for the 12 rounds.

"Also I practice having the ability to [punch] four times, not just once.

"Concentrate, take your time, pin him down.

"It's a fight for the brain. Knowing what you've got in front of you and knowing how to deal with it.

"You can either be aggressive, corner [him], throw everything at it. Or take your time, be clever, then knock [him] out."

Undefeated Ukrainian Usyk, the former undisputed cruiserweight champion, is stepping up to heavyweight in a bid to become only the third boxer ever to reign in both divisions.

Joshua will carry substantially more weight into the ring (at their last weigh-ins, respectively, he was nearly two stone heavier than Usyk) but is trying to lower his own size to match Usyk's nimbleness.

"I do look at my weight but I'm not trying to make weight because I'm a heavyweight," he said.

"I tailor my training. I am getting a lot of experience, I've been fighting good fighters for a long time, I've studied them and learned about their training camps.

"I've learned how to condition my body for specific fights.

"I'm looking trim for this fight.

"I'm fighting a guy who is a 12-round fighter. So it would be silly of me to go in there bulky with my muscles screaming for oxygen.

"I've been training like a 15-round fighter in this camp. I will be well-conditioned to fight. That is key.

"What happens when I train that way? My body adapts and takes its natural form. This is the form it has taken."

Joshua has had to recruit sparring partners to replicate Usyk's southpaw stance, including Irish prospect Thomas Carty and Germany-based Shokran Parwani.

"I want good sparring, tough sparring because you practice how you perform," Joshua said.

"We get in some really good sparring partners. You don't want to leave it all in the gym. But as long as you train with purpose, you are going to learn.

"Adversity is when you find out who you are. So I put myself in vulnerable positions and get comfortable.

"Guys with more power than me, quicker than me, a longer reach than me, a quicker jab than me. Through the process, I develop as well.

"It is a process that I am going through, adapting to a southpaw."

*SKY