DALLAS — Cooper Flagg’s long-awaited NBA debut arrived with all the anticipation of a new era — and all the hard lessons that come with it.

The Dallas Mavericks’ No. 1 overall pick finished with 10 points and 10 rebounds in a 125-92 loss to the San Antonio Spurs on Wednesday, a night when Victor Wembanyama, two years removed from his own shaky debut, delivered a 40-point, 15-rebound statement.

Flagg admitted his first game didn’t meet his expectations.

“Not great,” he said. “Obviously, I didn’t play incredibly well. But you got to move past it and try to focus on Friday (against Washington). It’s basketball. It’s not always going to go your way. It’s not always going to be perfect. But you got to adjust and be better on the fly.”

He found a brief rhythm late in the third quarter, scoring three straight baskets, including a reverse layup through contact. But for most of the night, the rookie looked tentative, struggling to find his pace in the Mavericks’ offense.

Anthony Davis, who finished with 22 points and 13 rebounds, sympathized with Flagg’s early jitters.

“It’s Game one. He’s still a rookie,” Davis said. “When Game one comes around, packed stadium and national TV game – everything (on social media) was No. 1 pick Cooper Flagg and Wemby matchup. So you’re hearing it. First-game jitters when it’s time for the real thing. He’ll be fine.”

Jason Kidd, who has seen plenty of rookies take their first lumps, said Flagg’s composure stood out even if his stat line didn’t.

“I thought Cooper played within himself,” Kidd said. “He took what the defense gave him, was making plays and diving on the floor. He’s one that’s not going to go out there and shoot every time he touches it. He tries to play the game the right way.”

Kidd added that the box score didn’t tell the story of Flagg’s effort.

“I thought he came out in the third and tried to be aggressive,” Kidd said. “As a rookie, he did fine. He’s going to learn from this game. We all will. And we’ll be better next time we take the floor.”

The Mavericks shot just 37.3% from the field, were outscored 68-26 in the paint, and gave up 31 fast-break points. Those numbers, Kidd noted, were a bigger concern than any rookie struggles.

“I like the way he played,” he said. “He’s going to be one of the best players to play this game. For him to see as a rookie how they’re playing him, to be able to go back and watch the tape – because he’s going to see it again – so he can get better … with a double-double to come out as a rookie is not bad.”

Flagg said Kyrie Irving, sidelined with a knee injury, pulled him aside during the third quarter with advice to “keep your head up” and move on to the next possession.

“I felt a lot of support,” Flagg said. “The fans were great and had a lot of energy, but we got to give them something a little bit more to stay hyped for, so that’s on us.”

The crowd made sure Flagg felt welcomed. During the national anthem, when the words “our flag was still there” rang out, fans shouted “Flagg” instead.

“That was kind of cool,” Flagg said with a grin.

Daniel Gafford (ankle), Kyrie Irving, and Danté Exum missed the opener, while rookie Miles Kelly was inactive. Kidd said Gafford remains “sore” but will be reevaluated Thursday.

The Mavericks face the Washington Wizards on Friday, hoping to turn the page — and for their newest star to take his next step.