About the work on Southpaw, Horner said: "It's just a movie I've never done before. I thought it would be really challenging. It'll be really edgy, but it will be very simple. No big orchestras. The big stuff takes care of itself. The director did a brilliant job, and it's stunning to look at, and well photographed. And there have been a lot of boxing movies obviously, fighting movies, but they're looking for something deeper than just the surface."
"It's a little bit unusual I would say. There are atmospheric moments with a simple piano motif and at the other end of the scale it's full out aggression. And then there's everything in between. Lots of colors", says Simon Rhodes (sound engineer) about the soundtrack.