Speaking at Tuesday's final press conference, 'AJ' said he has no worry about what weight he will come in at, adding that he has been feeling great in the build-up to the heavyweight unification clash, to be shown live on Sky Sports Box Office.
"If I've got £20 in my pocket, I believe Anthony Joshua knocks Joseph Parker out for sure," the WBA 'Super' and IBF world champion began.
"Every fight before this has been a learning fight, and every camp a learning camp.
"I learned from the Klitschko fight that I shouldn't use camp to get fit. I took everything I didn't know then into this camp. I've been working solely on my technique and ability for this one.
"Then I fought Takam, who was game... he was a lot shorter, he was in great shape. I wanted to control him and win. I knew there would be a big 2018 on the horizon.
"Every fight is a blessing, and every one will have reason in the long run.
"Parker is a champ and has done well... he will add something to my life journey. It'll be over Sunday, and I will look back and learn from it and move forward."
Joshua is confident of getting another knockout victory to extend his perfect career record, but the 28-year-old insists that he is preparing for a hard-fought 12 rounds.
"Parker has two arms, to be simple, but he is quick and can take a punch, that's what I've heard.
"Your weight depends on who you fight, if they're taller or short and stocky. I don't know what my weight will be, but I feel great.
"One fight at a time. I don't get all this talk about Wilder. I'm looking at Parker, who's a lively challenger. He's a champion for a reason. If I'm victorious, then I can look at future plans. For now, my future stops on Saturday.
"I don't want to lose. The fear of being defeated keeps me going.
"I'm preparing for a 12-round fight, which isn't a problem to go the distance. I believe I will knock Parker out for sure."
Parker was also in confident mood, and the unbeaten New Zealander had his say ahead of Saturday's showdown.
"It's great to be here, we've had a great build-up and a great camp. I can't wait to put on a great display on March 31," the WBO champion began.
"I'm confident, sharp, and my movement is better than ever. I'm taking those belts back to New Zealand.
"Joshua is a great champion and we respect him and what he's achieved. We love challenges. It's whoever is going to put on the best display on fight night.
"It's my time, I'm young, sharp and am determined to win. I'm here to be part of history, doing it for my team, family and country.
"I'm going to beat AJ, I haven't decided how I will win. These belts are mine."