Mark Ronson gets ''messed up'' when he thinks about working with Stevie Wonder.

The 'Uptown Funk' hitmaker was left ''speechless'' when the legendary singer agreed to lend his vocals to 'Uptown's First Finale' - the first track on the producer's new album 'Uptown Special' - and still can't believe the 'Superstition' star agreed to the collaboration.

Discussing the track, he said: ''The melody to this piece was completely inspired by the first set of lyrics that Michael [Chabon, novelist] sent me. And although I loved the lyrics, for some reason I kept hearing the melody as if it were being played by Stevie Wonder with his signature harmonica tone.

''His harmonica playing can really turn me inside out, just as his singing does.

''Anyway, I thought what the hell and sent a 'hail-Mary' letter to his manager with the song ... and a few months later, he recorded it!

''When I first heard it, it was one of the most emotional experiences I've ever had. I was dumbfounded, speechless, whatever word you want to use, I was all of those things.

''I still can't believe somewhere in a studio in Chicago one night, Stevie Wonder actually recorded a piece of music that I wrote. I've listened to it a hundred times and it still messes me up when I play it.''

Mark also revealed another track on the album, 'In Case of Fire', was inspired by singer/songwriter Rufus Wainwright.

In a track-by-track guide to the album for the Guardian, he wrote: ''I wrote this guitar riff while working on Rufus Wainwright's last album, 'Out of the Game'. It was partly inspired by a cello line he wrote for the song 'Jericho'. I really loved it but it didn't fit his record and I didn't know if I'd ever get to use it. But then a year or so later, I came up with the verse chords (inspired by some Michael Chabon lyrics that we never used) and everything seemed to fit together pretty well.''