DALLAS -- The Dallas Mavericks typically introduce only their starting lineup as part of their pre-game ritual. But before Wednesday's regular-season opener against the San Antonio Spurs, every player's name was called over the loudspeaker.

When it was finally Cooper Flagg's turn, Mavericks in-arena voice Sean Heath rumbled, "Cooper Flagg ... at GUARD."

Mavericks coach Jason Kidd has maintained since June that he wouldn't hesitate to put the ball in Flagg's hands. On opening night, Kidd did exactly that, starting Flagg next to Klay Thompson, P.J. Washington, Anthony Davis and Dereck Lively II in a lineup where every player was between 6-foot-5 and 7-foot-1.

The Mavericks' big unit is still very much a work in progress. Flagg, who was playing out of position, was held scoreless in the first half and finished with 10 points (on 4-of-13 shooting) and 10 rebounds in his NBA debut. Davis scored 22 points on an inefficient 7-of-22 shooting.

Victor Wembanyama, the former No. 1 pick who's now in his third year with the Spurs, stole the show. The 7-foot-something Frenchman scored 40 points, grabbed 15 rebounds and blocked three shots in San Antonio's 125-92 win.

"He's incredible," Flagg said about facing Wembanyama. "He's a different player. You can't know what it's like until you're out on the court with him. It's something I've never seen before. He was great tonight. But we have to do a better job of trying to take away some of his looks. Can't foul him as much as we did."

Wembanyama rampaged to the rim like Giannis Antetokounmpo and feathered in jumpers like Kevin Durant. He was an unstoppable combination of force and finesse. The Mavericks didn't do themselves any favors by putting forth an anemic offensive effort. They attempted 21 3-pointers and turned the ball over 16 times.

The Mavericks averaged 91.1 points per 100 possessions, meaning that, statistically, they had a worse offensive performance Wednesday than they did in any game last season.

"It starts offensively," Kidd said. "We have to be better offensively. And that will help our defense."

Knowing that Kyrie Irving would spend much of this season recovering from knee surgery, the Mavericks signed D'Angelo Russell in June. Russell made an All-Star appearance in 2019, and while he hasn't been back since, he is still a productive player who addresses some of the Mavericks' shortcomings. Russell made 226 3-pointers as a member of the Los Angeles Lakers in 2023-24, for example.

And yet, on this shooting-starved Mavericks roster, Russell came off the bench in his first game with the team. He wound up playing 15 minutes. He scored six points on 1-of-6 shooting.

Before the game, Kidd said he wanted to avoid labeling Russell as a sixth man. He said Russell might start at certain points this season, or he might be the Mavericks' eighth man, which was the case against San Antonio.

"He's going to get enough minutes to help us win," Kidd said. "That's why he's here. That's what we believe."

Dallas held a two-point lead on San Antonio with 3:30 remaining in the first half, after Wembanyama sent Davis to the free-throw line. Wembanyama had three fouls, but the Spurs stuck with him anyway. That was a smart decision, as they ripped off a 15-4 run to close the first half. Flagg committed one of his three turnovers during that run. Spurs guard Stephon Castle poked the ball away from him with 1:21 left in the half.

Earlier in the quarter, Castle stole the ball from Flagg on a similar play on the right side of the floor.

Flagg didn't get his first basket until the 11:42 mark of the third quarter. He came off a dribble handoff and made a 20-footer. Flagg next scored at the 2:44 mark in the third, but by that point, the game had slipped away.

"I think we just got a little stagnant," Flagg said. "It's early. We have to keep working on that. Figure it out and get our flow a little bit better. But I think a lot of it comes from getting stops as well. Have to get stops so we can push it in transition a little better."

Afterward, Kidd criticized his team for not passing the ball enough. Flagg, he said, was one of the few Mavericks players who wasn't hunting for his own shot.

"I thought Cooper played within himself," Kidd said. "He took what the defense gave him."

It's evident Kidd has great belief in his 18-year-old rookie. Kidd trusts Flagg so much, he made him one of the Mavericks' primary ball handlers right from the jump. Flagg didn't look great Wednesday, but almost none of the Mavericks players did. This team is loaded with frontcourt players but is thin at guard until Irving returns. That imbalance means it's likely Flagg will continue playing an unfamiliar position.

"I like the way he played," Kidd said. "I'm not going to sit here and change his thought process. He's going to be one of the best players to play this game."

Cooper Flagg's debut (at guard!) falls flat as Mavericks struggle against Spurs