LAS VEGAS — Cooper Flagg made his professional debut Thursday night in the NBA Summer League and celebrated an 87-85 win over Bronny James and the Los Angeles Lakers.

Flagg finished with 10 points on 5-for-21 shooting, including 0 for 5 from 3-point range. He also had six rebounds, four assists, three steals and one block. Though Flagg struggled at times to find his groove, there were flashes as to why he was chosen No. 1 overall last month, doing plenty of little things that helped the Mavericks seal the win, including a key block near the end of the game.

READ: NBA: Cooper Flagg looks comfortable in Dallas

Flagg swatted DJ Steward’s attempt with 1:10 left in the game, and Ryan Nembhard made a 3-pointer at the other end to give Dallas the 87-85 lead.

“I couldn’t really get into a rhythm, it’s a different environment, obviously very different from college, it’s probably very different from what the real NBA is gonna be like,” Flagg said after the game. “The coaches had a lot of confidence in me. They’ve been telling me they want me to experiment, try some new things, and I was trying to be aggressive, and that’s new for me too.

Dallas Mavericks forward Cooper Flagg (32) drives the ball against Los Angeles Lakers guard Bronny James (9) during the first half of an NBA summer league basketball game Thursday, July 10, 2025, in Las Vegas. (AP Photo/David Becker)

“I would say that might be one of the worst games in my life, but we got the win, that’s what really matters to me.”

Flagg strolled into UNLV’s Thomas and Mack Center at 4:17 p.m. on Thursday, wearing Dallas Mavericks gear, bright white New Balance shoes, and an emotionless look on his face as he passed through security.

READ: NBA Summer League opens in Vegas with Flagg vs. Bronny duel

Roughly 45 minutes later, he wore the same stone-cold face as he came out for warmups shortly after 5 p.m.

“I was obviously a little nervous, it’s a new environment, a lot of new fans and whatnot,” Flagg said. “So I was a little nervous, a little excited, but just happy to be here. It’s a dream come true, so I’m just trying to enjoy the moment.”

His fans more than made up for it with plenty of energy, electrifying the jam-packed arena that cheered loudest when he was announced as a starter in his first Summer League game.

Flagg missed his first two attempts of the game, picked up his first foul just 46 seconds into the game, and gave the crowd what they’d been anticipating, going one-on-one with fellow fan favorite James.

READ: Cooper Flagg selected by Mavericks as No. 1 pick in 2025 NBA draft

James buried his first attempt over Flagg, and then hit a 3-pointer after the 6-foot-8 Duke product missed his second attempt to give the Lakers a 5-0 lead.

Flagg excited the crowd at the 4:30 mark of the first quarter, jamming home his first points.

Early in the second quarter, Flagg nearly sent every fan in the building into a frenzy when he made a spin move into the paint and attempted a one-handed slam dunk over 7-foot Christian Koloko. The ball caromed off the back of the rim and still drew plenty of oohs and ahhs.

Generally filled with Lakers fans when the team plays in the summer, the arena was full of emotion with a fair share of Mavericks fans in attendance to see the 2025 National college player of the year.

Like 15-year-old Baer Epple, 15, who was seated with his father Chad in the third row from the court, donning Dirk Nowitzki’s Mavericks jersey.

Epple said he’s been following Flagg since before his Duke days, beginning with his junior year at Nokomis Regional High School in Newport, Maine.

The 15-year-old who is in Las Vegas from Seattle for an AAU tournament said he’s been a Mavericks fan for roughly four years.

“Even more of a fan now that they got Cooper Flagg,” Epple said. “Hopefully he does good, that’d be pretty cool to see. I don’t want him to be like a bust or anything.”

Mavericks coach Jason Kidd told The Associated Press before the game he was looking for nothing more than effort and grit in his team’s opening game, as he wanted them all playing hard.

“This summer league is a little different when you have this type of turnout,” Kidd said. “But the guys have had a couple practices. There’s going to be some turnovers. I just want to see how they respond to a couple of mistakes being made, no one’s gonna play a perfect game and be unselfish.”

As for his prize draft pick: “We’re all excited,” Kidd said of Flagg. “Seen enough of him on tape, so now it’s good to see him on the floor.”