However, New Zealander Parker is also unbeaten in his 24 fights and brings with him the WBO belt.
A crowd of 80,000 is expected and Joshua says Parker will have never heard anything like the noise that will be generated.
“It took me a few times to get used to it,” Joshua, who has a 20-0 record, told the BBC.
“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.”
Whoever wins will become a three-belt heavyweight champion and Joshua says the high stakes will create an electric atmosphere in the Welsh capital.
“This is history,” Joshua said. “This is a unification fight with two heavyweights undefeated and it’s in the UK.
Twenty times out of 20 I’ve been victorious, so expect the same routine.”
Parker’s promoter David Higgins said Joshua is rattled and warned that Tuesday’s pre-fight news conference will start without Joshua if he arrives late, as he has done in the past.
“He’s rattled and the press conference tomorrow is all part of that,” he told Sky Sports.
“We will be in control of that press conference.