Watch: Demi Lovato talks new album and 30th birthday on 'Fallon'

Aug. 17 (UPI) -- Superstar singer Demi Lovato appeared on The Tonight Show Starring Jimmy Fallon on the eve of their 30th birthday to talk about their upcoming tour to promote their new studio album Holy Fvck.

The tour will be the singer's first in four years.

"I did have nerves, I was like, 'Can I still do this?'" Lovato said. "I need to get the rust off for sure because I'm about to hit the road. It was really, actually, nerve-racking."

The singer went on The Tonight Show Tuesday evening as part of a three-day 'Tonight Show takeover' with the show. They will also work with Fallon as a guest host of the show on Wednesday.

Holy Fvck will be released this Friday, and Lovato joked that people should expect "live music" during the upcoming tour.

"My music is more rock now," they said. "So I'm not doing -- even my older songs kind of have a rock flare to them. They're not pop anymore."

"I was always [influenced by rock] in my teen years, so I feel like I'm just going back to my roots now," Lovato added. "My first album, my first and second album, they had more rock influences, and here we are."

The singer also talked about their propensity to do cover songs in their shows, one of which, the Goo Goo Dolls signature "Iris," will be on the set for Lovato's upcoming tour.

In a coming together moment, another one of Lovato's influences, Kelly Clarkson, recently covered one of Lovato's songs, a fact they described as a "big deal."

"For her to cover my song, years later, was just a full-circle moment, because I also used to cover her songs when I was younger, as well," Lovato said.

The Tonight Show appearance additionally coincided with the singer's 30th birthday, and Lovato said that they were "excited" about the upcoming year.

For her birthday, Fallon presented Lovato with a cake, and the audience sang happy birthday.

The singer ended their night on The Tonight Show by giving a performance of their song "Substance" off of their new album.