KYRIE IRVING’S FACE beamed with a big smile as he approached Cooper Flagg near the Dallas Mavericks’ bench, a stark contrast to the American Airlines Center scoreboard at that moment.

It was midway through the third quarter of the season opener, and hardly anything had gone as hoped for Flagg at that point of his heavily anticipated NBA debut. He had more turnovers than points as Dallas trailed the San Antonio Spurs by 15 when Flagg stepped back onto the floor after a timeout before stopping to listen as Irving approached him, the veteran clapping animatedly and offering good vibes along with words of encouragement.

“Just keep your head up!” Irving told Flagg.

Irving, like teammate Anthony Davis, understands the glare of the spotlight that comes with being the No. 1 pick in the NBA draft. But they began their NBA careers with the Cleveland Cavaliers and New Orleans Pelicans, respectively, two franchises that were in the early stages of a rebuild. Flagg’s situation is a far cry from that norm as he arrived in Dallas only a season removed from the Mavs making an NBA Finals appearance. He joined a veteran-heavy roster that has internal win-now expectations even with Irving still months away from returning from knee surgery.

“The first thing you tell him is to have fun and enjoy yourself,” Irving told ESPN during the preseason. “The work is just getting started, but it is pretty unique in terms of the situation he’s in. But being a No. 1 pick is still going to come with the pressure, still going to come with a lot of the inner thoughts that you want to impose on the team. You want to let everybody know who you are, and you want to earn everybody’s respect. And that’s what it takes to be in this league. There’s no boys allowed.

“For me, it’s just making sure he doesn’t get overwhelmed or it’s not too much for him.”

The first week of Flagg’s career featured mixed results as coach Jason Kidd tossed him into the deep end, starting the 18-year-old at point guard, a position the rookie had never played.

There have been moments when Flagg’s franchise-changing potential has popped, such as his poster dunk over Toronto’s Sandro Mamukelashvili on a fast break. That was the highlight of Flagg’s first NBA victory, when he finished with 22 points and no turnovers, joining Kobe Bryant as the only players in NBA history with a 20-point, zero-turnover outing before turning 19.

There have also been stretches when Flagg has faded into the background. He was scoreless in the first half of his debut and didn’t record an assist in the game, a blowout loss to the Spurs, when reigning Rookie of the Year Stephon Castle’s pressure defense made initiating the offense difficult. Flagg sat out in crunch time, save for a couple of late defensive possessions, and finished with only two points and no assists again in a loss to the Oklahoma City Thunder the night after his terrific performance against Toronto.

“He’s 18 years old,” Kidd said. “He’s going to look good; he’s going to make some mistakes. He’s going to learn from winning and losing, but being in this seat early on in your career will only make him better as we go forward.”

The challenges for Flagg aren’t just on the floor. His lone season at Duke, where he was perhaps the most hyped recruit in the prestigious program’s history, prepared Flagg as well as possible for the expectations and demands on a No. 1 pick widely billed as a generational prospect. But he has the added pressure of joining a franchise that is still reeling from the most controversial trade in NBA history as he navigates fame and playoff expectations.

“I mean, it’s a lot mentally,” Flagg said after his first win. “It’s a lot. I’ve been through a lot over the last couple months. It’s been a whirlwind, so just trying to take time to adjust and adapt.

“It doesn’t always go perfect right away. So just figuring it out day by day, game by game, minute by minute how I can help my team in the best ways. I think I’m starting to get more comfortable for sure.”