This is the first single from French electronic pop singer Charlotte Gainsbourg's second studio album, IRM. Charlotte is the daughter of British actress and singer Jane Birkin and French singer Serge Gainsbourg. "IRM" is French for "MRI" and the album title was chosen to reflect Gainsbourg's experiences of 2007, when she had brain surgery following a brain hemorrhage.
IRM is a collaboration with Beck. This song, which Charlotte describes as "a classical pop song," is a duet between her and the American alternative rock singer-songwriter. Gainsbourg already had a connection with Beck as his father, David Campbell, had arranged the strings on her previous album, 2006's 5.55. She told Mojo October 2009: "I met Beck just before I started the last album at a White Stripes concert. He was working with (5.55's producer) Nigel Godrich in LA. I hadn't thought of working with him as I was making 5.55 with Air. Then we met again two years ago."
"Piano Man" was inspired by Billy Joel's time playing at a piano bar in Los Angeles. The "real estate novelist" was a guy who always talked about writing a book, but spent all his spare time in the bar.
"Lean On" was originally sent by Major Lazer to both Rihanna and Nicki Minaj's camps as a slower reggae track. After both parties rejected the tune, Major Lazer recruited Danish singer MØ to supply vocals and recorded it themselves.