The two go toe-to-toe on August 20 in Saudi Arabia and there’s even the possibility that the Ukrainian could come into the fight heavier than his opponent.
The 35-year-old is favourite to retain his titles after he dominated the initial bout between the fighters in September of last year at the Tottenham Hotspur Stadium.
Usyk is training in Dubai ahead of the fight and he bumped into former world champion Amir Khan, who has confirmed he’s looking bigger.
Speaking to Seconds Out, Khan said: “He looks a lot bigger, I mean he was telling me that he’s put on an extra 15 kilos since he last fought AJ.
“So, we’re going to see how much strength he’s going to be having. He looks a full-on natural heavyweight. He is big and looks very strong.
“He nowhere near looked like a cruiserweight, he looked like a nice full blown-up heavyweight.
“He was strong at the weight, when he was hitting the pads and stuff and you can see the definition on his body.
“He’s very thick and you can see it’s solid muscle that he’s got.”
If the Ukrainian has really put on 15 kilos since his first encounter with AJ then it could mean that he comes in heavier for the fight than the British fighter.
The 18 stone that Usyk possibly has gone up too is more than the 17st 2lb that Joshua weighed in the first bout.
Next Friday’s weigh-in could prove to be extremely intriguing due to this added aspect as it was never thought that the current world champion could exceed Joshua’s weight.
The former cruiserweight was doubted when he stepped up to the bigger weight due to his smaller frame.
It was thought that competing with the likes of AJ and Tyson Fury would prove to be a step too far due to their bigger size.
But after September’s stunning win and Fury’s possible retirement, the whole division has opened up for the southpaw.
The 32-year-old Joshua had to regain the belts in the past when he lost to Andy Ruiz Jr, but it will be a much tougher ask this time around.