Jessica Biel & Justin Timberlake (FameFlyNet)

THE X FACTOR: Demi Lovato arrives at the taping of THE X FACTOR in Greensboro, NC. Sunday, July 8. THE X FACTOR airs on FOX. CR: Ray Mickshaw / FOX.

THE X FACTOR: Demi Lovato arrives at the taping of THE X FACTOR in San Francisco, Sat. June 16. CR: Ray Mickshaw / FOX.

THE X FACTOR: Demi Lovato arrives at the taping of THE X FACTOR in Austin, Texas on Thurday, May 24. CR: Frank Micelotta / FOX.

THE X FACTOR: Demi Lovato arrives at the taping of THE X FACTOR in Kansas City Friday, June 8. THE X FACTOR airs on FOX. CR: Ray Mickshaw / FOX.

TEEN CHOICE 2012: Presenter and co-host Demi Lovato during the TEEN CHOICE 2012, airing LIVE Sunday, July 22 (8:00-10:00 PM ET live/PT tape-delayed) on FOX at the Gibson Amphitheater, Universal City, CA. CR: Michael Yarish/FOX

THE X FACTOR: L-R: Britney Spears, Simon Cowell, Demi Lovato and L.A. Reid. CR: Nino Munoz / FOX.

THE X FACTOR: Demi Lovato arrives at the taping of THE X FACTOR in Providence. RI, Tuesday, June 27. THE X FACTOR airs on FOX. CR: Stew Milne/ FOX.

TEEN CHOICE 2012: Presenter and co-host Demi Lovato during the TEEN CHOICE 2012, airing LIVE Sunday, July 22 (8:00-10:00 PM ET live/PT tape-delayed) on FOX at the Gibson Amphitheater, Universal City, CA. CR: Michael Yarish/FOX

Singer Demi Lovato greets her fans as she leaves the ITV Daybreak Studios on April 2, 2012 in London, UK. (FameFlynet)

RIO DE JANEIRO, BRAZIL - Thursday April 19, 2012. Demi Lovato rocks the mic as she performs at Citibank Hall in Rio de Janeiro. (Pacific Coast News)

MILAN, ITALY - Sunday April 1, 2012. Singer Demi Lovato seen posing for photographers and fans while presenting her new album Unbroken at the Mondadori Multicenter in Milan Italy. (Pacific Coast News)

Celebrities arrive at the Teen Choice Awards 2012 held at the Universal Amphitheater in Los Angeles, CA on July 22, 2012. Celebrities arrive at the Teen Choice Awards 2012 held at the Universal amphitheatre in Los Angeles, CA on July 22, 2012. (FameFlynet)

"Camp Rock" star Demi Lovato took a trip in a London Taxi to see all the picture-postcard sights that the West End has to offer on a drab April 3, 2012 in London, UK. She stopped outside Buckingham Palace and in Piccadilly Circus to view the statue of Eros. She also went past the Houses of Parliament, Big Ben, Trafalgar Square, Downing Street and Horse Guards before arriving at HMV Oxford Street for a personal appearance. (FameFlynet)

'X-Factor' judges, Britney Spears, Demi Lovato, LA Reid and Simon Cowell arriving for the first day of auditions at the Erwin Center in Austin, Texas on May 24, 2012. (FameFlynet)