Nikola Jović slid underneath the screen. Mikel Brown Jr. didn’t bother moving closer. Thirty-two seconds into his preseason debut, Brooklyn’s No. 6 pick rose from 28 feet and buried a 3-pointer.

The Nets lost their chance at an unbeaten preseason Wednesday, falling 144-128 to the Miami Heat at Kaseya Center to finish 3-1. Brown, finally back from a sprained left ankle, spent 18 minutes showing how much he could add to an offense already scoring with ease.

After missing Brooklyn’s first three exhibitions, the rookie guard finished with 15 points, three rebounds, two assists and two steals on a minutes restriction. He made four of seven shots, including two 3-pointers, and committed two turnovers. His most encouraging work came when Miami tried to press him.

Three times, Brown threaded pocket passes to Mo Wagner’s lead hand as two defenders converged on him off a ball screen. Each arrived early enough for Wagner to catch in stride and attack a four-on-three advantage. Brooklyn created open shots from those possessions, including a 3-pointer and a lob dunk.

Brown’s two official dimes couldn’t account for every opening he created. Brown moved the ball before Miami could recover, giving Wagner room to attack and his teammates time to turn the initial advantage into an open shot.

“I love his communication, how engaged he was with his teammates. I thought it was a very well-played 18 minutes for him,” Nets head coach Jordi Fernández said postgame.

The 20-year-old followed his opening 3-pointer with a baseline drive, then struck again from deep late in the third quarter. He fired a pass to Chaney Johnson, took the return and drilled a 26-footer. Early in the fourth, he swiped a Davion Mitchell pass and raced in for a two-handed slam.

The composure stood out because Brown had spent much of training camp learning to stop on two feet, recognize when a simple pass was there and resist the temptation to force plays. The ankle injury left him watching teammates build chemistry through three games.

“I feel like I have no choice but to be patient. I want to be out there so bad,” Brown said after practice earlier in the week.

Brown’s passing instincts surfaced in Summer League, when his first significant contribution was finding Tyler Bilodeau for an open 3-pointer. Against Miami, those reads held up under more demanding pressure. Brown moved quickly, but his reads rarely looked rushed.

Now Fernández has to find him a place among Brooklyn’s young guards. Egor Dëmin, increasingly decisive as a shooter and attacker after making strides late last season, scored 17 points and made four of seven 3-pointers. Fellow second-year guard Nolan Traoré added 12 points and five assists. Brown’s range gives him ways to play alongside either guard, and his ability to initiate gives Fernández more combinations to test.

Keon Ellis’ perimeter defense also has to factor into those decisions.

The Nets have been objectively awesome on offense this preseason. Michael Porter Jr. led Brooklyn with 27 points on 9-for-17 shooting. Wagner scored 15 on 6-for-7 shooting, and Julius Randle added 15 points and five assists despite going 4-for-13. Brooklyn finished with 28 assists Wednesday and scored at least 114 points in each of their four exhibitions.

Miami shot 59.1% and outscored Brooklyn 62-38 in the paint. Eleven of the Nets’ 18 players are at least 6-9, yet their size provided little resistance around the rim. Giannis Antetokounmpo amassed 20 points, 15 rebounds, nine assists and three blocks in fewer than 24 minutes. Day’Ron Sharpe contributed 11 points, six rebounds and four assists, but five fouls limited him to 17 minutes.

Brooklyn surrendered at least 30 points in nine of its 16 preseason quarters, including 43 in Wednesday’s third.

“Just defense. I mean, it was a very poor defensive game,” Fernández said.

Miami scored 69 in the first half and 75 after halftime. Fernández didn’t soften his assessment.

“That’s unacceptable. And if we want to be a competitive team, we have to play better defense than that.”

With 5:41 remaining Wednesday, Fernández emptied the bench. Brown had checked out at 8:22, his minutes restriction fulfilled. And after three games of waiting, he’d finally given his coach a reason to want more.

The Nets open the regular season at home against the Charlotte Hornets on Oct. 21. Fernández has defensive problems to address and rotation decisions to make, including how quickly Brown can take on more responsibility.