Someone should have taken a picture of the halftime scoreboard and submitted it to “Believe It Or Not.” The lowly Nets were having their way with mighty Golden State, building a 16-point lead at the break with some of their best basketball of the season.

But visions of grandeur vanished in a flurry of second-half turnovers as the Nets wilted under defensive pressure from the Warriors, who dominated down the stretch on their way to a 117-101 victory Thursday night at Barclays Center.

The Nets committed 26 turnovers leading to 32 Golden State points, including 18 for 25 in the second half alone.

After winning the first half so convincingly against the defending Western Conference champions, losing the second half by a 68-36 margin was utterly crushing to the Nets. The Warriors lead the NBA in steals, and they reinforced that dominance with 19, including 12 by their big three of Steph Curry (five), Klay Thompson (four) and Kevin Durant (three).

Much of the time, it was the Nets’ big three that was victimized as Brook Lopez lost six turnovers, Jeremy Lin had five and Sean Kilpatrick committed four. “They turned up the defensive intensity, turned up the energy and were really aggressive on the defensive end,” Nets coach Kenny Atkinson said of the Warriors. “We have to do a better job of protecting the ball. That was the story. They flooded the paint on our drives and switched on our pick-and-rolls.”

Clearly, the Warriors were embarrassed defensively in the first half, but they quickly made up for it by pressuring the Nets, who committed seven turnovers and shot 1-for-4 in their first 11 second-half possessions to fuel a 17-2 Golden State run that cut the Nets’ lead to 67-66. The Nets didn’t score until Lopez’s layup at 8:39 of the period.

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Atkinson called a timeout during that stretch, trying to stop the momentum, but it didn’t help. The Warriors turned 11 Nets turnovers in the third quarter into 17 points and an 88-84 lead going to the final period, and just kept going from there.

“They doubled Brook in the post and blitzed Jeremy in the pick-and-roll,” Atkinson said. “Those guys have to do a better job of kicking it out. It’s a work in progress, but we need to find more solutions.”

After sitting out the loss in Toronto on Tuesday night for a prescribed rest, Lopez provided a major boost for the offense. He scored 23 of his 28 points in the first half to lead the Nets (7-21) to their impressive lead.

Lin added 10 points, 11 assists and eight rebounds, Rondae Hollis-Jefferson scored 13 points and Bojan Bogdanovic had 12.

Durant topped the Warriors (26-4) with 26 points despite a 1-for-7 night from three-point range. Thompson had 23, Curry scored 15 and Zaza Pachulia added 15 points and 14 rebounds.

Lopez got the Nets going with 10 points in their opening 20-12 run, and the Nets ended the first quarter with a 34-33 lead. “It was team-wide,” he said. “We knew we had to hit first because of the kind of team they are. They have a lot of firepower, and we had to be aggressive.”

Lopez blamed himself for contributing to the avalanche of turnovers that began the second-half onslaught when he threw a bad pass, and he admitted the young Nets got a little rattled against such a top-level team.

“It is a young team,” he said. “We did a good job trying to stick with it. But we became less aggressive, and they got a lot of easy stuff out of the turnovers.”

It doesn’t get any easier for the Nets, who will face the defending NBA champion Cavaliers in Cleveland on Friday night.