DETROIT — One moment, it sounded like New Year’s Eve inside Little Caesars Arena. 

Pistons fans believed their team was headed to a Game 7 in New York with a chance to advance in the playoffs for the first time in 17 years. 

The next, it felt like a church, the building silenced by Jalen Brunson’s deft crossover and cold-blooded, top-of-the-key 3-pointer. 

Suddenly, the Knicks were the ones celebrating, ending Detroit’s best season in nearly two decades on Brunson’s game-winning 3 with 4.3 seconds remaining Thursday. 

“Jalen’s shot, what can you say?” coach Tom Thibodeau said after a thrilling, 116-113 finish to this chaotic and tightly-contested opening-round playoff series in six games. “He’s at his best when his best is needed. He’s done it all year. That’s what makes him special.”

For the third straight season, the Knicks are advancing in the playoffs, thanks to Brunson’s 40-point, seven-assist masterpiece.

They hope they can get past the Eastern Conference semifinals this time, though Thibodeau’s team will be a heavy underdog against the reigning champion Celtics.

Game 1 is Monday night in Boston. 

“I think we’ve grown, we’re continuing to grow,” Josh Hart said. “So it’s going to be a heck of a battle.”

On Thursday night, the Knicks were savoring this gritty victory. They blew leads of 15 points in the second quarter and 11 in the fourth.

They trailed by seven when Brunson started the series-closing 11-1 run with a 3-point play. He added a basket inside and Mikal Bridges pulled the Knicks even with a tip-in. Just over a half-minute remained. 

The Knicks got a stop and Brunson went to work.

His crossover sent Ausar Thompson, the Pistons’ impressive young defensive stopper, several feet to his left. Brunson had a clear view of the basket, the kind of look he rarely misses. 

“I was wondering if it was gonna be a swish or he was gonna hit some part of the rim,” Karl-Anthony Towns said. 

He sank the shot, quieting the large crowd that had taunted him throughout the series. They called him a flopper, screamed “F— you, Brunson,” booed him on every touch.

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He had the last laugh as the Knicks took all three games in Detroit, winning three consecutive road playoff games for the first time in franchise history. 

“I don’t really go and think, ‘All right, I’m gonna make this move right here.’ It’s just instinct,” Brunson said of the last shot. “He beat me to the spot. He cut me off. Just went back the other way, and I found a lot of space, and I was able to take a shot.”

Brunson was the hero, and he had plenty of help. Bridges turned in his best game of the series, scoring 25 points.

OG Anunoby added 22 points and three steals, and Hart chipped in 13 points, 10 rebounds and four assists. Towns, despite an off shooting night, added 15 rebounds. Most importantly, the Knicks got the needed stops down the stretch, holding the Pistons to just one free throw over the final 2:35 while forcing three turnovers.

They locked down young Detroit star Cade Cunningham (23 points, eight assists) when the game was up for grabs. 

The talk throughout this matchup was of Detroit’s grit and physicality. That these Knicks lacked the toughness of last year’s version.

However, they rallied from fourth-quarter deficits in three of their victories.

They took a haymaker on Thursday, a 20-2 Pistons fourth-quarter run, and landed the final punch, earning a shot at the powerhouse Celtics. 

“We’re a tough group. Everyone likes to paint us as not, but we’re a tough, physical group,” Hart said. “This was a physical series. It was a grueling series. And I think we showed our physicality, our toughness, but also our mental toughness. The way we handled adversity. 

“During those adverse situations, we banded together. We didn’t play as individuals. It was a great series for us.”