For the first time in league history, the NBA Draft will stretch over two nights beginning Wednesday at Brooklyn’s Barclays Center. But make no mistake — this is the Cooper Flagg draft. Much like Caitlin Clark electrified the WNBA with her arrival last season, Mr. Flagg enters the NBA with seismic expectations and plenty of star power.

The Dallas Mavericks are expected to make official what everyone has long assumed: Mr. Flagg will be the no. 1 overall pick announced by Commissioner Adam Silver. “It’s a surreal feeling to believe where I came from and what I’m about to do,” Mr. Flagg said during a media session Tuesday in Brooklyn. “Being here is surreal. I don’t think it’s really set in yet. I’m just trying to go through each moment and enjoy it.”

Ms. Clark brought much-needed attention to the women’s game with her deep shooting and overall ability. Mr. Flagg may do the same for the NBA, whose television ratings were down much of its recently completed season. His versatility to play several positions, his basketball IQ, and his competitive edge have caught the attention of seasoned NBA scouts and veterans.

“Cooper’s brain is right on par with guys like LeBron [James],” a former NBA player and coach, Brian Scalabrine, who’s worked with Mr. Flagg since his early teenage years, said. “They just process the game differently.”

At 6-foot-9 with a 7-foot wingspan, Mr. Flagg, 18, has the size of an imposing post player, the agility of a small forward, and the decision-making of a point guard. At Duke, he averaged 21 points, 7.6 rebounds, and 5 assists in the NCAA Tournament, where he led the Blue Devils to their first Final Four appearance in three years.

“People might get caught up in the numbers,” Orlando’s head coach, Jamahl Mosley, said. “But I think he’s going to be one of those guys who makes everyone around him better. He’s just that kind of player.”

Mr. Flagg got the opportunity to test his skills against top NBA talent when he was invited to join the Select Team that scrimmaged in Las Vegas against Mr. James, Stephen Curry, and Team USA as it prepared for the Paris Olympics. From all accounts, Mr. Flagg held his own.

“It was a good learning experience for me to go in there and learn from everybody,” he said. “There was a ton of Hall of Fame players. That confidence I got from playing with them let me know I can play my game and do what I do.”

Mr. Mosley, who coached the Select Team, marveled at Mr. Flagg’s maturity and work ethic. “He was asking a ton of questions,” Mr. Mosley said. “Defensively, that stood out. Offensively, he was always trying to make the right play. His brain was clicking.”

A native of Newport, Maine, Mr. Flagg left home at age 15 to attend Montverde Academy, a program in Florida known for developing Division 1 and professional basketball players. “My mom once said, ‘If you’re the best player in the gym, you need to find a new gym,’” Mr. Flagg said. “I’ve always wanted to be in gyms where people challenge me. That’s how I get better.”

Mr. Flagg knows he’ll be in the spotlight once he reaches the NBA, especially in a world driven by social media and hot takes. “It’s a little bit of pressure,” he admitted. “You get the media and people having opinions about your life and everything about you. For me, it’s a lot of motivation. Hearing people talk about you is a good thing, no matter what.”

After Dallas, the draft order continues with San Antonio, Philadelphia, Charlotte, and Utah making the top five choices barring trades. After Mr. Flagg, most mock drafts list the top prospects as Dylan Harper of Rutgers, V.J. Edgecombe (Baylor), Tre Johnson (Texas), Ace Bailey (Rutgers), and Kon Knueppel (Duke). None of those players approach the complete package that Mr. Flagg offers.

“What you’ll see in the first month, the first year, is only the beginning of what his potential is,” a Duke alum and former NBA player, Grant Hill, said.

The Mavericks’ fan base was shattered last season when star player Luka Doncic was traded to the Los Angeles Lakers. Now they’ll have a new hero to cheer when Mr. Flagg arrives.

“Going into whatever situation I’m going to go into, I’m just going to try to be myself,” Mr. Flagg said. “I’m going to try to push myself to get better and better every day. I’m not worried about living up to expectations. I’m just going to be myself.”