The I Gotta Feeling hitmaker has worked with artists including Michael Jackson, Britney Spears, Sir Mick Jagger and Jennifer Lopez among others, and he admits the movie star is the next big game he wants to record with.
He says, "I would like to work with Robert Downey, Jr... That guy sings."
The actor has sung on several soundtracks and he released an acclaimed album in 2004, titled The Futurist.
The actor showed his approval as he posed alongside his blooming producer partner Susan.
The couple, who wed in August 2005, are expecting their first child together ? a boy ? in February.
The sequel to the 2009 blockbuster held its gala opening at the Village Theatre in Los Angeles last night.
Joining 46-year-old Downey Jr, who plays the titular sleuth, was director Guy Ritchie.
The pair warmly embraced on the red carpet and later lined up alongside cast members Rachel McAdams, Jared Harris and Noomi Rapace for a group shot.
Elementary greeting ... Downey Jr embraces director Guy RitchieA Game Of Shadows sees Sherlock and newly-married Watson (Jude Law) hooking up with a new character, gypsy Sim (Rapace), to pit their wits against arch enemy Professor Moriarty, played by Harris.
The first instalment in 2009 marked a return to form for Ritchie ? who'd suffered both critical and commercial lashings with movies Revolver and Swept Away ? banking ?330million at the box office.
