On October 31, Christophe-willem.com announced the possibility that the album would contain a duet with Kylie Minogue on the track called "Sensitized".

The title "Caféine" was made official on February 6, 2009, but other rumours appeared.

The first said Jennifer Ayache, singer from French rock-band Superbus, gave Willem a song named "Dansez".

The second is about a French adaptation from "State of Grace" by Britney Spears, a leftover song from the Blackout recording sessions.

In some interviews, Willem makes his duet with Kylie Minogue known, the track is produced by Guy Chambers just like "Heartbox".