Sam Fischer's duet with Demi Lovato was meant to be with another artist.

The 29-year-old singer is releasing 'What Other People Say' with the 28-year-old hitmaker and admits it was by complete chance that it happened as the writing session was "supposed to be" for someone else.

Speaking to The Sun newspaper's Bizarre column, he said: "The writing session was actually supposed to be for another artist, but that artist didn’t turn up. Demi heard it and immediately connected with the lyrics. I felt like this was something that she really wanted to say and share from her own personal perspective. But she hadn’t found the words to do that yet. So it’s kind of nuts. Demi has one of the best voices in the world. My personal opinion is that she’s never sounded better than on this song. Her voice is other-worldly.

"She’s been through so much. And to have the ability to be able to almost relive what you’ve gone through to put into a song and share that with people and be able to use your experiences to help others is such a beautiful gift that she possesses."

Meanwhile, Sam recently hailed Demi as the "bravest" person he knows.

He shared: "It's a real gift for her to be able to share everything she's been through, because I Imagine every time she thinks about it and every time she talks about it, it hurts. But she is giving millions of people around the world a chance to not feel alone in their struggle. Demi's so brave - one of the bravest people I know - and she's so talented. Demi Lovato is one of the greatest vocalists in the world so to be able to sing with her is such a dream come true for me."