Get ready for the duet of the century tweens! Demi Lovato is well under way preparing for her new come back album with the help of musical giants such as Timbaland and Sebastian, but it doesn't stop there. Demi has also brought in the biggest gun of them all.. (well in teen world at least) - Justin Bieber! Sebastian teased fans on twitter yesterday, saying how a "special guest" has been stopping by for a "super duet". This urged fans to guess like crazy who it might be, and shortly thereafter Sebastian responded to one fan, "@AndreaLovesSwag u said justin bieber that is a very very good guess.”

We think Demi has just secured herself a golden ticket to a VERY successful come back album!