It will be Briton Joshua's fourth stadium bout but, with 80,000 fans expected, represents a new level of interest for New Zealand's Parker.

"It took me a few times to get used to it," Joshua told BBC Radio 5 live.

"It's an experience he hasn't faced yet. It is daunting, it is overwhelming.

"You have a fighter that will block out the noise, which takes a whole heap of energy. Then you have a fighter who rides the wave, which can leave you too excited.

"The fight is won or lost in training camp but the last bolt is screwed on during the spell from your changing room to the first bell."

'This is history'
Joshua told BBC Sport he has recently been watching videos of Lennox Lewis, who held the IBF, WBA and WBC titles in 2000.

Since then, only Tyson Fury and Wladimir Klitschko have held three heavyweight titles at one time.

And as well as three of the four heavyweight titles, Joshua and Parker will put undefeated records on the line in the Welsh capital.

"This is history," Joshua told BBC Radio 5 live's boxing podcast.

"This is a unification fight with two heavyweights undefeated and it's in the UK.

"It's going to be electric. You know when you come here to fight myself, you know there's going to be blood, a fighter hurt and 20 times out of 20 I've been victorious, so expect the same routine."

'Parker will be 30% better'
Joshua has made subtle tweaks to his training since defeating Carlos Takam in October.

He now focuses on boxing during morning sessions, with running or strength work later in the day. The reverse of his old routine aims to see him fresher when doing technical work under the guidance of trainer Rob McCracken at the English Institute of Sport in Sheffield.

And Parker - undefeated in 24 bouts - has undergone changes of his own after having surgery on both elbows late in 2017, a move which his camp claim has led to a 20% improvement in his punching since he out-pointed Hughie Fury in September.

"He is dangerous," added Joshua. "He's a king where he is from so he has that pride on his back as well. He has to represent the heritage and that's important.

"I just believe that when people come to fight me, they come 30% better. If he's known to be quick, he will be rapid. If he's known to take a punch, I will have to throw the kitchen sink at him.

"They all come with that bit more ambition. I have to make sure that when I'm throwing my best shots, that I'm confident to know who I am dealing with."

'I've fought them both' - Analysis
GB Boxing super-heavyweight and Joshua's sparring partner Frazer Clarke

I've boxed AJ and Parker. AJ and I boxed in 2009 at my local sports hall.

I was meant to box a guy from Nottingham as an amateur, a bit of a pudding if I'm honest. It's common in amateur boxing you get pull-outs. I was on the scales, a few rolls of fat on me and this shadow comes over me, a guy who looks like he's been chiselled out of stone. It's Anthony Joshua.

We had a proper good tear up. Straight away I knew this was a proper fighter who would go a long way.

When I was on the Great Britain squad, I fought Joseph Parker in India. A good fight and I'm told he remembers it. It was close, he got it on points and was probably a little bit fitter at the time. He carries similar things now to then, a lot of combinations, fast hands, a vicious puncher. I think these two will gel and it will be one of the best fights yet.

I can't look past Joshua. I have done the whole camp sparring with him. We have sparred 60 or 70 rounds in this camp.

In the build-up to this, the Klitschko and Takam fights have done so much for him as a boxer. They have taught him being big, strong and fit is not enough at world level. You have to have a brain, know what to do when times get tough. He also learned the importance of patience and I think he has found his optimum boxing weight. Look at him now, he's gliding, flowing, fast. This man can do it all.