With only a fortnight remaining till British heavyweight champion Anthony Joshua takes on Kiwi sensation Joseph Parker at the Principality Stadium in Cardiff, experts and fans have already started making big predictions about the clash.

Ahead of the duo going head-to-head in Wales on March 31, critics of Joshua have repeated expressed doubts over the world champion's stamina and admitted Parker could exploit that weakness in the unification bout.

The WBO title-holder, too, was among those who claimed he remains doubtful about Joshua’s durability inside the ring.

Parker and his trainer Kevin Berry accused Joshua of lacking energy as fights progress and are keen to prove it when the pair go toe-to-toe.

Asked to react to the questions on his stamina level, Joshua insisted he is similar to other greats in the division and had the perfect reply to his sceptics.

“I find this interesting about my stamina because I have like 20 fights now, majority were knock-outs," Joshua said, per The Express. "Then I had a scrap against [Wladimir] Klitschko, right.

"Tell me any heavyweight you know that hasn’t gone into a war, Foreman-Lyle, Holyfield-Cooper, that hasn’t felt the pressure and the heart rate go sky high when they’re in a big fight?

“[Carlos] Takam, I controlled him for 10 rounds with ease. He bust my nose, I couldn’t even breathe through my nose.

“That one fight is defining my stamina? It’s boring. I don’t really rate it.”

AJ advised whoever is doubting his credentials in the ring need to read up about the sport.

He added: “People asking about my stamina, people asking about my chin, people asking about this and that, go back and study boxing.

“Then you’ll get to know what it’s like for heavyweights to be in a real slug fest, what it’s like for heavyweights to take power punches. Then you’ll see what I’m going through is just what these people you have hanging on your bedroom wall were going through.

“We’re all the same, we’re all in this game. They’ve paved the way for me to walk down and I’m walking it just like them.”

Joshua has always claimed that every fight is a learning experience and the contests of last year have made him understand which facets of his game needs improvement.

But he will also know that he can ill-afford to be learning on the job when he finally faces another unbeaten world champion in the form of Parker.