Transcript for Zion Williamson on pressure of the NBA draft
All right, looking forward to this. Robin sitting down with 18-year-old Zion Williamson. Zion as everyone calls him. Right. Basketball sensation whose life is about to change in an instant. Projected to be the number one pick in the draft. He may have always had a basketball in his hands. You can tell that, but there's so much more to Zion than what you see on the court. He is a grounded young man who knows where he came from and where he's going. Look out, the windmill with the left hand. Reporter: He's 6'7", 285 pounds of jaw-dropping athleticism. Oh, my goodness. He was three feet above the rim to hammer it home relationship the gravity-defying Dunks throwing fans into a frenzy. And moves so fast his shoes can barely keep up. Slipping and injured is Zion Williamson. How many people can blow out a shoe on a court? I'm not sure. Reporter: At just 18 years old Zion Williamson is being called the future of basketball after an explosive freshman year at duke university. He declared for the NBA draft in an emotional Instagram post this April. I hope to pursue my next dream and declare for the 2019 NBA draft. Reporter: Tomorrow he is widely expected to be the number one pick at the NBA draft. How high can you go? Everyone is saying with the first pick the New Orleans pelicans are going to say your name. What goes through your mind when you think about that, number one pick? I never saw myself as even being a top three, top four pick and for people to think I could go one means a lot to me. I just want to get drafted, period. Number one picks, Lebron, Shaq, Zion. Going by first name only, don't even need a second name, I mean, those will some big shoes to fill. Are you ready? Those are some big shoes to fill but I'm not looking to fill just be the best Zion I can be. I know you're aware that the New Orleans pelicans traded Anthony Davis, so if, indeed, you are the number one pick, you will be the face of that franchise. Are you ready to take on at your age a role like that if it should happen. Gosh, who said that, I'd be the face? I think I'd be ready because I just love this game and I'm a competitor, whatever I'm doing, I want to win. I think the same for the players that are already there. When is the first time you had a basketball in your hands? Probably before I can quite remember. Reporter: He was just 5 years old when he told his mother he wanted to be a professional basketball player. What was it like being coached by your mom? She was the hardest coach I've ever had. Don't let mom fool you. Be in the car ride home after my middle school games and I would be like that was a great game. My mom would be like, good game? You missed a pass. That was the best for me. Reporter: And it paid off. By the time he was in high school he was already garnering legions of fan, even drake posting a picture sporting a then 16-year-old Zion's Jersey. How do you stay grounded with everything coming your way? There are times when this wasn't here. There were no interviews. There were no fans. The gym was empty. Actually when you're in an gym you were in an outdoor court, me and my stepdad and think when it was just me and myself and -- But then you walk in the door I didn't even know you were here. I could hear that you were here by the reaction from those young kids and I know that you spend time with kids. Why is that so important to you to do that? Because I was a little kid at once and, you know, having the chance to meet an NBA player or even a college player when I'm like 5 or 6, I mean, I know it would meanry lot so just to talk to one of those little kids or sign it, I try to do it as much as possible. Who has helped you to get to where you are right now. My mom an stepdad. They've been there since day one. They've always told me that I can achieve my dream. I say check -- don't make me embarrass you. He is definitely ready. He's going to go far in the NBA. You're not going to play nice. Don't buy that smile. He has that killer instinct. Who are some players in the NBA right now that you look to as a role model to help you at this next level? I mean, gosh, I won't view them as a role model when I get there 12k3w4r oh, okay, I love that. But people I respect for, Lebron because since day one he had the highest expectations and he's excited all of them on and off the court. Russell restbook and kawhi Leonard because he don't say much, he just handles his Ben 'goes on about his day. Hours away from now your life is going to change. I don't see it so much as my life changing. I'll still play the game I love and the circle I have around me that it will keep my life the same as it's always been, just probably more people calling my name. He didn't Google me and see my game. Google, man. I loved how he responded. Me too. Such respect. He is so down to Earth. He is so humble. His family was there and his 5-year-old brother was draining shots on the court but he -- I told him that he had been nominated and broke some tus to him and said you've been nominated for an espy for best college athlete and he was like, wow. You're about to be number one draft pick and that's his passion for everything that he does. I love how he Hammed everything. So grounded and so ready. Respect. Yeah, right, confident, not cocky. You better Google robin Roberts. The older I get, the better I was. Can you see more of my exclusive interview with Zion on "Nightline" and the NBA draft on ESPN tomorrow night starting at 7:00 P.M. Eastern. Better tune in early so you don't miss Zion.
This transcript has been automatically generated and may not be 100% accurate.