Justin Timberlake and Cameron Diaz to Star in Shrek 3  5/2/05

Pop star Justin Timberlake will star alongside real-life girlfriend Cameron Diaz in Shrek 3 as the voice of one of the animated characters.

The singer is lending his vocal talents to the role of the young King Arthur in the fantasy feature, which also sees Eddie Murphy and Mike Myers returning to play Donkey and lovable ogre Shrek respectively.

And producer Aron Warner has quashed rumors that screen beauty Diaz, who plays Princess Fiona, persuaded him to cast Timberlake - claiming the young pop star was just right for the part.

He says, "Our desire was to get somebody who is visible and had their own persona to bring to the table.  "Justin fit the bill perfectly."

Timberlake has already appeared in the cartoon franchise - in Shrek 2, a poster of "Sir Justin" on the wall of Princess Fiona's bedroom flashes across the screen.