"This fight will inevitably bring out the best in Joseph Parker. This is what he needs. We've never had a fight where people have said 'you ain't winning this fight, you're getting knocked out, this guy is too big and too powerful'. This is the motivation that will bring out the best in Joe.
"I've seen it in the gym. I'm not asking for something he can't do."
The insults about Parker's weight from Joshua on television recently probably haven't harmed his motivation either. "Joe is one of these guys who, even when he takes an extended period of time off… he gets into fight shape very quickly," Barry said.
Parker was in the gym immediately after his whirlwind media trip to London and has kept himself extremely busy since.
"His whole days have been filled with training," Barry said. "He applies himself very well. We've got a very busy itinerary for him. On some days he's doing four or five things. They're not all physical things; as well as the boxing and the running and the strength work and physio it could be a mental coach session."
The mental side of the equation was described by Barry as "beyond important", and more on that soon. In the meantime Barry believes a perfect storm is building, one which will erupt in front of nearly 90,000 people at Principality Stadium.
"There is huge pressure and public expectation on Joshua," Barry said. "He's the guy with the 20-0, 20 KO record. The pressure is on him to knock Joseph Parker out and this is the Joseph Parker that we've marketed and promoted as the guy who has never been off his feet in the amateurs, sparring or professionals.
"He's also putting a lot of pressure on himself. He and his team are saying, 'after this we're fighting Tyson Fury, we're fighting Deontay Wilder' – they're looking past Joe and we're delighted by that attitude."
Parker and his team have based themselves in a new gym about 500m from Barry's Las Vegas home which is cutting down significantly on travelling time and helping with Parker's rest and recovery.
It means there is more time to focus on the mental side of things, among others. Parker last year linked with Ceri Evans, the man whom the All Blacks believe was crucial to their winning the 2011 World Cup, and Barry said that side of the preparation was more important than ever.
"We're trying to be complete," Barry said. "We want to be strong in all aspects. We are putting ourselves in a position we're we've never been before. I think Joshua and his team are thinking once we get out there in front of 86,000 people that Joseph Parker is going to fall apart because he's never experienced that before.
"What they don't realise is that the Joseph Parker I know, it wouldn't matter if it was 80 people, 800, 8000 or 80,000. It's the same guy, it's the same guy preparing and the same guy walking to the ring and fighting in the ring.
"One of his greatest strengths is the control of his emotions. If we don't win this fight it will be because we're not good enough… it won't be because we're overawed in front of the 86,000 people that are there.
"We didn't have a great 2017," added Barry. "We didn't lose the belts - that was the most important thing. Joe didn't bring his 'A game' to either of his fights. I understand why people look at that and say 'that Joseph Parker will be destroyed by Joshua'. If we turn up like the guy who fought [Razvan] Cojanu and [Hughie] Fury we're going to be in for a very difficult night. I know that's not the Joseph Parker who will turn up on March 31. I need the real Joseph Parker to stand up."
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