Joseph Parker claims Anthony Joshua's training methods don't appear to be working given that he has looked tired in his recent fights.
The 26-year-old will put his WBO heavyweight title on the line against WBA (Super) and IBF champion Joshua in an eagerly-awaited unification showdown at the Principality Stadium in Cardiff on 31st March.
Parker has admitted to keeping tabs on Joshua's training methods at Sheffield's English Institute of Sport over the past week.
And, while the New Zealander claims the British fighter's preparations look cutting edge in terms of training for fights, he doesn't believe they are working.
Every time he's been asked to go on to the later rounds, he's really struggled so that's a question for his training staff.Joseph Parker
Joshua was taken to the later rounds for the first time in his 20-fight professional career in his most recent wins against Wladimir Klitschko and Carlos Takam respectively.
And Parker, who has won all 24 of his fights to date, including 18 KOs, warned the 28-year-old to be ready to go the full 12 rounds in their bout or face the consequences.
He told Sky Sports: "When you watch him, when you see all the training, it's like they are doing all this new training and it looks really hard, and it looks intense, and it looks the type of training that will prepare you for 12 rounds.
"But, in saying that, just maybe their team need to work on a few things. We know that our team has a good structure and a good training programme that will allow us to fight 12 rounds, if we need it.
"But I'm not sure why he tires, that's something he has to sort of figure out."
Parker, who has gone the distance in four of his last six fights, added: "I see videos posted everywhere of him doing the most sophisticated, new age training methods that man has ever seen and, yet he's looked very tired in his last couple of fights.
"Every time he's been asked to go on to the later rounds, he's really struggled so that's a question for his training staff.
"He wouldn't want to be slowing against Joe, because I can promise you this. Joe will be coming on in the later rounds."
Joshua is 1/7 to win the fight, while Parker is priced at 5/1 to come out on top, while it is 7/2 for the bout to go the distance.
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