The French DJ found the singer/songwriter through her solo single 'Breathe Me', but they didn't collaborate until 2011, when Sia sang on his track 'Titanium', which went on to become a huge worldwide hit.
Speaking of 'Breathe Me', David told Q magazine: ''I discovered her with this record. She was pop but kind of underground pop, which is in a way not really logical. After that we made 'Titanium' together. She's probably the hottest writer in the world right now.''
Sia - whose full name is Sia Furler - has seen her career climb to new highs since working with David, with her writing hits for Flo Rida, Christina Aguilera and Rihanna's recent single 'Diamonds', but David said she was on the verge of quitting the music business when he asked her to sing on his track.
He said: ''When we recorded 'Titanium' she was like, 'Well David, I don't want to be an artist anymore. I'm done with this life. I just want to be a songwriter. I don't want to tour. I don't want to do anything like this anymore.'
''When I heard her voice on the track, I was like, 'That is insane. No one is going to be able to do better than this.' So she was like, 'OK. Last one!'''
Sia has recorded five solo albums, but it is not known if she has any plans to continue with her solo career, or only work behind the scenes in the future.