Demi Lovato threw a Nashville "house party" with Billy Ray Cyrus on Wednesday (12.07.17).

Billy Ray Cyrus and Demi Lovato [Instagram]

Billy Ray Cyrus and Demi Lovato [Instagram]

The 24-year-old singer is bringing her 'Houseparty Tour' to different cities across the US to promote her new single 'Sorry Not Sorry' and decided to surprise her fans and invite the country music singer, 55, to perform when she landed in his hometown.

The stars delighted party goers at the Mansion at Fontanel -- a 33,000-square-foot log once occupied by Barbara Mandrell - and Billy later shared a picture of the pair on Instagram, writing: "Thank you so much @ddlovato for havin' me as your special guest tonight for your Nashville #SNSHouseParty! Let's get #SNSToNumber1!‬ #SNS (sic)"

He added: "You ladies rocked the house tonight!"

During the night Billy - who is Miley Cyrus' father - performed his world-famous hit 'Achy Break Heart' while Demi sang and danced alongside him and the brunette beauty said she was so happy that she got to catch up with her friend's dad and old neighbour.

She said: "When I was about 15, we were neighbours, and I met him through Miley, obviously...I think (his cameo was) perfectly fitting for Nashville."

The 'Confident' singer also said she was shocked at how passionate her fans are about her music.

Demi told USA Today Network Tennessee: "It's been really hectic, but it's also been really fun. Any time I'm with my fans, it makes me feel fulfilled.

"Yesterday, when I performed ('Sorry Not Sorry'), they were still learning the words. They knew the chorus, but they didn't quite know the verses. Today I went and performed in Birmingham, and they knew every single word. I don't even learn a song that fast, and I'm a professional singer!"

Meanwhile, Paris Hilton features in Demi's new video for 'Sorry Not Sorry' and took to Twitter to gush about the fun they had making the promo.

She said: "So much fun raging with my girl @DDLovato's to her new single & my new summer anthem #SorryNotSorry! #SavageAF (sic)