DALLAS — Any old basketball won't do. Tarris Reed Jr. wants the one he played with.

As Reed settled into a seat facing the San Antonio Spurs' lockers at American Airlines Center Saturday night, De'Aaron Fox put his hand on his shoulder. The veteran point guard had already promised the rookie something of great value. Now he had to follow through.

"Fox said he's going to give me the game ball," Reed said, smiling in the Spurs' locker room after their 122-106 win over the Dallas Mavericks. "I'm waiting on my game ball."

After Fox assured Reed he'd receive the real game ball, the rookie continued fielding questions about the first real minutes — and points — of his NBA career. Granted, he saw the floor against the Oklahoma City Thunder in the team's regular-season opener, but only for one minute before the final buzzer after Mitch Johnson decided the game was a wash.

This time, Reed checked in to begin the fourth quarter of a three-point road game.

"I mean, it's surreal," Reed said. "It's a blessing. I didn't think I was going to get in."

Facing the shorthanded Mavericks, the Spurs entered Saturday's contest eyeing an opportunity to get their first victory of the season. Yet midway through the third quarter, they watched as the 14-point lead they built evaporated as Dallas kept its foot on the gas.

Luke Kornet, who finished the night minus-18 in 14 minutes on the floor, wasn't entirely to blame, but his struggles as the lone center on the court were difficult to overlook.

When it came time to give Victor Wembanyama another breather, Johnson opted instead for Reed's fresh legs. The rookie entered the game with something to prove. It worked.

"That was probably the best three minutes anyone played," Spurs guard Dylan Harper said of Reed. "He came in and just played hard. He played with the kind of intensity we needed."

In the 3:38 Reed spent on the floor to begin the final period, the Spurs took their 92-89 lead and turned it into a 103-94 advantage. Reed logged three rebounds and two points, which came off a feed from Devin Vassell at the rim for his first career make.

The simplicity of his impact made all the difference for the Spurs, who spent a majority of Reed's minutes on their feet, celebrating the moment with him from the bench.

"It's amazing, right?" the coach asked rhetorically, visibly fired up talking about his team's effort. "Tarris wasn't out there shooting step-back, between-the-leg 3s. He was just playing his ass off ... being physical ... it's contagious when you play the right way."

Added Harper: "I give props to him ... He was focused from a physical standpoint (and) a mental standpoint. And when his number got called, he kind of seized his moment."

Since he was drafted, Reed has prided himself on being able to add physicality and rebounding to the Spurs, who had only Kornet to lean on with Wembanyama off the floor. After seeing limited action during preseason, he began seeking ways he could improve.

Reed watched scout videos, studied film and prepared "as if he was going to play 30 minutes a night." If he did, he planned to make sure every inch of the glass was covered.

"That's my game," he explained. "That's what San Antonio brought me here to do."

A successful three-minute stint against Dallas doesn't instantly make Reed the Spurs' go-to option to play backup center for Wembanyama. It was, however, a meaningful step toward establishing trust with Johnson and the coaching staff. He's just got to stay level-headed.

"We talk about it quite a bit," Johnson said, asked about keeping young players accountable. "The current doesn't stop — it's just go, go, go. We always talk about acknowledging where we're walking out of and where we're walking into. We focus on where our feet are."

Reed's feet touched the floor underneath the chair where he fielded questions Saturday night. They hit the hardwood when Reed was called from the bench to check in at the start of the fourth quarter, and then walked back to the bench after the work was done.

"He understands it," Wembanyama said. "It was obvious. It was three big minutes. Three important minutes. His intensity shows he understands what it takes to be on the court."

Reed doesn't ask for much. But in his third career game, he got an opportunity.

Apparently, he's getting a game ball, too.