Justin Timberlake was barely 16 when he walked into Cheiron Studios in Stockholm, Sweden in 1996. The aspiring star was recording *NSYNC’s breakout single, “Tearin’ Up My Heart,” in the same room where songwriting legend Max Martin and the late Denniz Pop created some of pop music’s biggest hits. At the time, Andreas Carlsson — who would later help pen chart-toppers like *NSYNC’s “Bye Bye Bye” and the Backstreet Boys’ “I Want It That Way”  — was pursuing his own singing dreams, recording a solo record in the room next door.

“Justin Timberlake would pop in and I remember the first time we met, he said, ‘I want to do stuff that sounds like your music,’ which I thought was very sweet,” Carlsson recalls. “I said, ‘I think you’re doing fine already!’”

While Timberlake’s talent was clear to Carlsson early on, it was once he became involved in the band’s sophomore album, 2000’s “No Strings Attached,” when he realized the teen’s true potential. “There are stars, then there are stars,” Carlsson says. “The way Justin saw himself from a very early age was something I’d never experienced before. There was the athletic side, the politician, the incredible performer. He had this self-control that was very unusual for a young person. He was a bright shining star in every way possible — a master at everything he was doing. … I remember when we did ‘No Strings Attached,’ I said ‘That guy could run for president one day.’ He was enormously-driven, very gifted and had something very special about him. I felt that same thing with Jon Bon Jovi — that they’re more than just artists and have political qualities and the kind of drive you find in an athlete.”

Record executives weren’t necessarily looking for a solo star at the time, but Timberlake’s potential was apparent to Jive Records founder Clive Calder, when he and the label’s then-CEO, Barry Weiss, set out to sign the quintet (Timberlake, JC Chasez, Lance Bass, Joey Fatone and Chris Kirkpatrick) as they became free agents.

Having become suspicious of the group’s founder and manager, Lou Pearlman, whose shady financial dealings would be exposed in the coming years and result in prison time before his death in 2016, both *NSYNC and the Backstreet Boys were embroiled in a 1999 legal battle with the mogul, the latter forced to cut him in on a portion of BSB’s earnings. *NSYNC were able to break free of Pearlman’s contractual clutches and sever their recording deal with RCA Records. But Weiss says that regardless of the lawsuit, Timberlake was planning to nullify his contract upon turning 18.

It was around then when Weiss headed to Atlanta’s Chastain Park Amphitheatre to check out the group in concert. As the executive recalls: “We walked into Chastain Park and stopped halfway as the group was performing and I’ll never forget, Clive Calder looked at me and said, ‘It would be amazing if we can get the whole group. That would be the most amazing thing that could happen. But Barry, our worst-case scenario and why we’re going to proceed with this is that you see that young guy up there? That lead singer, Justin Timberlake? This kid could be one of the biggest solo artists in the world. And, that kid’s going to disaffirm his contract, so the worst-case scenario is that we’re going to have Justin Timberlake as a solo artist.’”

Weiss, now CEO of RECORDS, says he and Calder met with the group afterwards at the Ritz Carlton Hotel in the Buckhead section of Atlanta. While they had doubts about whether they would receive adequate attention by signing with the same label as their biggest competition, the Backstreet Boys, Calder and Weiss won them over.

Production on “No Strings Attached” kicked into gear soon after. “They were all gracious, fun and great to be around,” says Richard Marx, who wrote and produced the ballad “This I Promise You.” But Timberlake’s interest in and attention to the process made the singer stand out. As Marx recalls: “When I didn’t need him behind the microphone, he’d be down the hall in another studio recording demos and ideas. He was so focused. It’s no surprise at all that he became so successful.”

Guy Roche adds that despite only working with *NSYNC on one song, Timberlake’s drive and passion made a strong impression. “Justin was nervous and antsy, wanting to get down and record right away whereas the other boys were joking around and not in a hurry,” says Roche, who produced NSA’s “That’s When I’ll Stop Loving You.” “Justin was the uptight one. Even in those days, he wanted to get going and was pushing the others to do their work. He was like the boss. The leader. It’s pretty obvious why he was so successful.”

Musician Alex Greggs meanwhile recalls a more low-key Timberlake during his first meeting with the group at their manager Johnny Wright’s office in Orlando, Florida. Greggs and his late producing partner, Brad Daymond, had released remixes of previous hits like “Tearin’ Up My Heart,” which caught Chasez’s attention and led to the duo working on NSA.

“They were all very quiet,” Greggs says of his first impressions of the quintet. “I think they were so used to producers being the big people in the room. Then as time goes on, it changes and they walk into the room and the producers are the ones going, ‘Alright, the big guys are here!’ But in that beginning stage, it was cool because we got to do things with them that we wouldn’t have if they’d already been established. They were very receptive to everything we asked.”

“At first it I thought it was obviously JC who was the big star,” Greggs adds. “Then, within a week, I figured it would be both of them, and that Justin was going to be a great total act as well. I think everyone realized Justin was going to come out larger than life. It didn’t happen with JC, but that was more because of a bunch of things that didn’t go right with his [solo] record.”

Music legend Diane Warren agrees that Chasez, too, had the makings of a powerful solo artist. Warren wrote the NSA track “That’s When I’ll Stop Loving You.” She had previously penned the band’s Gloria Estefan collaboration, “Music of My Heart,” and was in the studio for both recording sessions.

“Both Justin and JC [stood out],” she says. “Justin may have become a bigger solo star, but I think JC’s a really great singer too. He’s fantastic. He’s really talented, but they all are.”

“No Strings Attached” sold more than 2.4 million copies in its first week, breaking a record previously held by the Backstreet Boys’ 1999 release “Millennium.” (Adele took the title in 2015 with her 3.38 million first-week sales for “25.”) *NSYNC followed up the the album with 2001’s “Celebrity,” then in 2002 announced a hiatus.

Timberlake wasted no time exploring his talents outside of the group, releasing his solo debut “Justified” in 2002 months after the group announced their break. At the time, he told the New York Times, there was “no reason my solo career and *NSYNC can’t coexist,” however it soon became apparent that *NSYNC wouldn’t be reconvening. In fact, the five have only reunited onstage once to honor, you guessed it, Timberlake at the MTV Video Music Awards in 2013. The group received a star on the Hollywood Walk of Fame in April 2018.

Timberlake has in the years between carved at a phenomenal career of his own. He has won 10 GRAMMY awards, four Emmys and sold more than 32 million solo albums. He has also pursued business and charitable ventures and released a book. On Friday, he was featured on Bass’ podcast, “The Daily Popcast With Lance Bass,” for a rare interview about his time with the group and the NSA era.

And, while Timberlake’s superstar destiny was clear to many who met him during those days, Weiss strongly believes his time with *NSYNC was a key factor in his success.

“It was absolutely critical because it gave him the ability to stretch out and know what he wanted to be as an artist, cut his teeth as a touring musician and in later *NSYNC records become a writer with ‘Girlfriend’ and ‘Gone,’” Weiss says. “Those are two records that Justin was the predominant writer on and ultimately they were the precursors to his solo career.”

For Weiss’ former colleague, current RCA Records co-president Joe Riccitelli, Timberlake always struck him as “nothing but positive and hardworking,” but two decades into their working relationship and friendship, it’s Timberlake the family man who has really wowed Riccitelli.

“I’ve had the luxury of working with him and promoting every single he’s released since ‘Bye Bye Bye,’” says the veteran promotion executive. “I’ve seen him grow from a teenager into an amazing man and my greatest experiences with Justin Timberlake have been more about the man and father he’s become than the incredibly-talented musician he is. As a dad myself there’s nothing more endearing than seeing a teenager turn into a man.”