Howie Dorough then helped welcome Twain, 53, to the stage before Nick Carter, Kevin Richardson and Brian Littrell joined in the sweet serenade, during which Twain beamed while singing along and blowing kisses to the boys.
This isn’t the first time Twain has enjoyed a night out with BSB.
She invited the group to join her for a stunning rendition of “From This Moment On” as part of her Winter Break special filmed in Miami, Florida, and airing on CBS in 1999. Twain penned the track after she lost her parents in a car accident and wanted to write an “eternal love song” in their honor.
Since then, Twain and the quintet have remained friends and fans of each other.
So, naturally, Twain hit up the band’s Larger Than Life concert long ago, hanging with the guys backstage and watching the hit-fueled residency show in February 2018.
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Backstreet Boys Make Plea for Bruno Mars Collaboration at 2019 GRAMMYs
However, this time the boys took a trip down memory lane by pulling the superstar and former Las Vegas resident onto the stage with them.
The epic #BSBVegas moment came as the group, who recently released their long-awaited new album, DNA, prepare to wrap up the record-breaking residency with final shows in April, before hitting the road on their DNA World Tour from May 11 in Lisbon, Portugal.
They're also hoping to get in the studio with fellow chart-topper Bruno Mars, telling ET about the dream collaboration while attending the 2019 GRAMMYs, where their catchy hit "Don't Go Breaking My Heart," was nominated for Best Pop Duo/Group Performance.
Meanwhile, Twain has collaborations with another Vegas headliner on her mind. She recently told ET that she hopes to soon fulfill her dream of having Celine Dion record one of her songs.
"One of my dreams has always been that she would record one of my songs. So, yeah, I'd love her to sing one of my songs," Twain shared. "I'm going to write one for her! I love her, she's extraordinary."