Karl Johan Schuster, known professionally as Shellback, is a Swedish record producer, songwriter and multi-instrumentalist. Shellback was listed as the No. 1 producer of 2012 on Billboard magazine's year end chart, and he also topped the list of their "Top 10 Songwriters Airplay Chart" the same year; he has won four Grammy Awards.

Karl Martin Sandberg, known professionally as Max Martin, is a Swedish record producer and songwriter. He rose to prominence in the late 1990s with songwriting credits on a string of hit singles, such as Britney Spears's "...Baby One More Time" (1998), the Backstreet Boys' "I Want It That Way" (1999), Céline Dion's "That's the Way It Is" (1999) and NSYNC's "It's Gonna Be Me" (2000).