The Backstreet Boys are back with the "Into the Millennium" Las Vegas residency at the Sphere and a new song, which dropped Friday.

The Backstreet Boys have announced a nine-date residency at the Sphere in Las Vegas called "Into the Millennium."

The 90-minute show was classic Shelton, as he rattled off hit after hit from his deep catalog, sipped booze from a plastic black cup on stage and often bantered with the crowd. During one moment, he noticed a fan’s custom-made t-shirt that said: "Still not a Swiftie. I’m a Sheltie.”