COLUMBIA, S.C. — Zion Williamson sat in his hotel room the night before his NCAA tournament debut pondering his shot to play on the biggest stage in college basketball.

“Wow,” the 18-year old said, “I’m really here.”

With a CBS camera dedicated to his every move, the most prolific NCAA player had one of the strongest tournament debuts in memory.

Williamson scored 25 points in an explosive performance to lead top-seeded Duke to an 85-62 win over North Dakota State in Friday night’s first-round game.

RJ Barrett led Duke with 26 points and 14 rebounds and combined with Williamson for an unstoppable 1-2 freshman punch. But it was Williamson who could not be contained in the second half and he turned a tight early contest into a Duke runaway in the first round of the East Region.

Williamson was disappointed in the Blue Devils’ sluggish first half as Duke led just 31-27 at the break. Teammates were in his ear, he said, telling the star to “be me.”

When that happens, there’s no one else in college basketball like Williamson.

He opened the half by driving on two defenders for a layup that drew a foul. He missed the free throw but Williamson answered with a monster slam.

The highlight, though, came moments later on Williamson’s breathtaking dribble-behind-his-back-after-chasing-down-his-own-steal layup.

The 6-foot-7, 285-pound freshman outran 5-foot-11 190-pound Vinnie Shahid of North Dakota State for the ball after he tipped it for a steal. Williamson then dribbled behind his back, briefly losing and regaining his balance with a hand on the floor. That cleared room for Williamson to get to the lane and go up and under for a layup.

Just like that, the Blue Devils were up 40-27 and cruising. The Bison (19-16) never recovered.

“In the second half, we played beautiful basketball,” Duke Coach Mike Krzyzewski said.

Barrett and Williamson gave Duke two players with 20 or more points in their NCAA tournament debut for the first time since Mark Alarie and Johnny Dawkins did it in 1984.

Barrett said Duke, which starts four freshmen, may been overly excited about the NCAAs. When they settled down and began to play, Barrett said, things came easier.

Shahid led the Bison with 20 points.

North Dakota State Coach David Richman knew Duke had the potential for a back-breaking run that would put his team on its heels. Richman was as awed by Williamson as everyone else. “Probably one of the best athletes I’ve seen with my own eyes,” he said.

Still, Richman’s spunky team held a 25-24 lead late in the opening half. That was when the Blue Devils settled for too many jump shots, Krzyzewski said, giving North Dakota State the chance to hang around.