Following a two-year pause on their DNA World Tour, the Backstreet Boys have resumed their worldwide trek with a four-night launch at Caesars Palace in Las Vegas. ET Canada was there as the boy band kicked things off with a bang, delivering seductive strip shows, tears, celebrity guests, nail polish parties and cute family appearances.

But it was the deep nostalgia bubbling throughout the two-hour show, which hits Canada from July, that ushered fans back in time and left them entranced in late nineties pop bliss.

The 32-song set paid heavy homage to the group’s Millennium era, during which they reigned the charts with hits like “I Want It That Way”. And while such favorites are a staple of any Backstreet Boys show, the DNA World Tour brings back deeper cuts from the period.

“There’s so many great songs in our catalog, but I love when we do an acapella set and sing ‘Don’t Wanna Lose You Now,’ from Millennium,” Nick Carter told ET Canada. “It was never a single, but was a really great song. That’s the epitome of being a true fan because if you’ve listened to the deep cuts from the Millennium era, you know the Backstreet Boys by heart!”

READ MORE: Backstreet Boys React To Machine Gun Kelly Throwing Up At Their ‘Millennium’ Concert

Inside The Colosseum theatre on Friday night, AJ McLean told the audience – which included *NSYNC’s Lance Bass and husband Michael Turchin – that Las Vegas is a “second home” for the group, who previously had a record-breaking Larger Than Life residency at Planet Hollywood. Kevin Richardson then teared up expressing how it felt to be back with the BSB Army.

“We’re so blessed to be here with you tonight,” he said. “It’s been two long, hard years. We’ve all been through a lot.”

For Richardson, recent months have been further clouded by the January loss of his mom, Ann, who also loved music and sung in choirs in her youth. She was likely on Richardson’s mind during opening night, when he choked up singing “Show Me the Meaning of Being Lonely,” a song partly inspired by grief.

“He’s an emotional guy,” McLean later said. “I love him.”

Richardson, 50, and McLean, 44, then switched gears with a strip show.

“The other guys are backstage doing a quick change, but how would you feel if we got changed right here … this is Vegas, right?” teased McLean, before stripping off from an open box. “Everyone who got seats up top – you’re gonna see the whole freaking enchilada!”

In another salute to the peak pandemonium the quintet faced around the millennium, fans then hurled panties and bras on stage as the singers continued getting dressed. McLean and Richardson chucked their boxers back in response.

After performing “Passionate” from DNA and 25-year-old hit “Quit Playing Game (with My Heart),” McLean sweetly saluted his mom, Denise, who was in the audience.

“I wouldn’t be here on this stage doing what I love today if it wasn’t for one woman – my mom,” he said.

Added Richardson: “Denise used to do our wardrobe, merchandise, she was the bus mom, she cleaned up after us. She traveled all over with us.”

The singers also reminisced about forming in Orlando, Florida, in April 1993.

“I was a very mature 19-year-old,” quipped Howie Dorough, 48.

“He was so mature he was the only Backstreet Boy with chest hair,” added Carter, 42. “He had all the hair and AJ didn’t have any, so he would paint on his goatee.”

Carter then teased Brian Littrell, 47, about how thick his Southern accent was when he joined the band.

READ MORE: Nick Carter Talks Christmas With Baby Pearl, ‘Boy Band Wars’ With Lance Bass & Backstreet Boys’ Touring Comeback

The musicians also performed solo snippets from DNA tracks, with Dorough singing “Chateau,” Littrell performing “Nobody Else” and Carter kicking off “The Way It Was.”

Carter wrapped Friday night celebrating his brother-in-law Corey Conrad’s birthday at Caesar’s Palace hotspot Omnia Nightclub, alongside Bass and Turchin. But the fun didn’t stop there for new dads, Bass and Turchin, who welcomed twins in October.

The couple returned to Caesar’s Palace on Saturday afternoon to attend a nail polish tutorial for McLean’s brand, Ava Dean Beauty. McLean launched the brand with close friend Josh Naranjo in 2020 and they recently introduced a make-your-own nail polish kit in collaboration with Taylor Made Polish, whose founder Vanessa Ungvarsky showed fans how to mix their own shades.

McLean created a new shade named “Bye Bye Bye” in Bass’ honor. “That’s going to be your biggest seller!” laughed Bass. The polish will be auctioned off to benefit Bass’ chosen charity, The Trevor Project, which helps LGBTQ youth.

Given that back in the day he was often frowned upon for wearing nail polish, McLean told us it felt “amazing” to not only have his own brand, but run an event attended by fans, boyfriends, moms and Bass.

“This is where I belong, in this space,” he said. “I’ve always been comfy in my own skin and expressing myself how I do, so to all the haters – you just don’t get it. I love who I am and who I’ve become and this is the best way to share it with the world.”

McLean also shared that he will hold similar events during the Backstreet Boys’ Canadian tour. He added that his sense of style is even partly-inspired by a Canadian – Vancouver native Ryan Reynolds.

With fans ready with their new nail polishes, it was back to The Colosseum for Saturday night’s final Las Vegas show, where Carter was excited to have his two-year-old daughter Saoirse attending her first Backstreet Boys concert.

“I love you!” Carter gushed as Saoirse watched him on the screen, waving frantically while seated with mom, Lauren, and big brother Odin.

The band are now looking forward to taking the DNA World Tour back on the road, with stops in Toronto, Vancouver, Edmonton, Saskatoon, Winnipeg, Ottawa, Quebec City and Montreal.

“It feels like I’m back home with the fellas, back in our element,” said McLean, who has spent his Backstreet Boys downtime performing with side projects, ATCK, “Back-Sync” and The After Party. “The crowd love is unlike anything we’ve had before because of how long we’ve been off the road.”

“I’m so looking forward to getting back to Canada,” added Carter, who recently collaborated with Jimmie Allen on “Easy.” “God, Canada’s so beautiful! There are so many memories, from starting out in Montreal and Toronto and being out there a lot before we were big in America. I love it up there and we have great fans and incredible memories.”