LAS VEGAS — The earthquake may have been the best part of RJ Barrett’s opening NBA night.

The game being called in the fourth quarter amid precautionary concerns about the swaying scoreboard overshadowed Barrett’s dud-of-a-debut.

Forcing many attempts, the lefty Duke product shot 4-for-18 — 1-for-8 from beyond the 3-point stripe — to tally 10 points.

Barrett admitted that “some guys got kind of tired I guess,” and maybe that had something to do with his poor shooting. But he made no other excuse.

“I’ve been working hard all summer, getting in great shape,’’ Barrett said following Saturday’s practice. “There’s nothing you can do to simulate a game like that. So, sure, I haven’t played a game in three months.

“Shots just didn’t go in. Tell me one player that’s had a great game every game. You know what I’m saying?”

The 6-foot-7 swingman also missed three of four free throws and had just one assist. His 3-point shooting (30.8 percent) and free-throw shooting (66.5) were issues at Duke.

The electric atmosphere that saw LeBron James, Anthony Davis and Floyd Mayweather on hand was no factor.

“Nah, I didn’t really care,’’ said Barrett, the Knicks’ No. 3-overall pick. “I was on a team with Zion [Williamson]. We got that every game, so it didn’t faze me at all.”

The Knicks rushed onto the bus after Friday’s game was called and did not make players or head coach Jud Buechler available for questions.

“There were ups and downs in the game for him,’’ Buechler said, according to the Knicks’ statement. “You expect that from a rookie. We saw a lot of things we liked. We will continue to encourage him to keep shooting and aren’t worried about his shot not falling tonight.’’

At least Barrett made it to the earthquake that occurred with 7 minutes remaining and the Knicks down six. Williamson was shut down in the second half with a sore knee and back and is finished at summer league.

Barrett hadn’t played since missing a key free throw with 5.9 seconds left against Michigan State to cost Duke a trip to the Final Four. His play was a little selfish, according to one NBA scout. The scout added, however, not to make too much of one game.

On one play, Barrett spun to the hole, was guarded tightly in the lane as Kevin Knox held up his hands, wide open at the 3-point line. Barrett took the contested shot and missed. Knox had the hot hand Friday, making 3 of 4 from downtown.

“I liked my shots, but first game, we’re going to figure it out,’’ Barrett said. “Just work it every day.”

Knox, who starred in last year’s summer league, posted 17 points.

“I just felt comfortable out there,’’ Knox told The Post.

The Knicks face the Suns on Sunday at 9:30 p.m., but Mikal Bridges has elected not to play. With their draft-day trade just becoming official, their rookies are Ty Jerome and Cam Johnson.

The Pelicans’ Williamson, shut down in the second half of Friday’s game against the Knicks with knee soreness, has been shut down for the rest of summer league, the team announced. The 285-pound Williamson looked out of shape in his nine-minute performance and Pelicans coach Alvin Gentry told NBA.com he also had back issues.

The Knicks’ second-round pick Ignas Brazdeikas played as advertised Friday — aggressive. The lefty wing went hard at the rim but wasn’t necessarily on target. He finished with five points on 2-for-8 shooting.