Britney Spears, Demi Lovato 'X Factor' judges

After weeks of speculation, Fox officially announced during its fall upfront presentation Monday that Britney Spears and Demi Lovato will join "The X Factor" as judges.

Both Lovato and Spears appeared with co-judges Simon Cowell and L.A. Reid at Manhattan's Beacon Theatre.

Said Spears: "I'm ready to find the true star."

Spears jump-started the most anticipated announcement of the day by about 20 minutes, sending out a Twitter pic of her and her fellow judges before Cowell and Fox Entertainment chief Kevin Reilly told the crowd that she and Lovato would indeed be joining the show.

In a statement sent to the media, Spears said, "I couldn't be more excited to join 'The X Factor' judging panel. I'm a huge fan of the show and now I get to be a part of the action. Simon and L.A. better watch out!"

Spears and Lovato are replacing Paula Abdul and Nicole Scherzinger.