Loving Justin Timberlake clearly can't keep away from girlfriend Cameron Diaz.

The singer is joining her for the third installment of Shrek, movie bosses have confirmed.

Shrek 3 producer Aron Warner excitedly revealed the singer has a role in the movie.

Justin will play a young King Arthur, a rebellious high school student with no interest in being king.

It's up to Shrek, voiced by Austin Powers star Mike Myers, to teach Artie how to act like royalty.

Diaz, the voice of Shrek's wife Fiona, had no say in Timberlake landing the job, Warner insists.

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

And when asked if he would dish the dirt on one of showbiz's hottest couples, he added: "I'm the last person to ask about gossip."

The Trousersnake - who has also got a part in the new Die Hard movie - will be joining stars such as Eddie Murphy and Antonio Banderas who also voice roles for the movie.

But movie fans will have to wait to hear his efforts - it is not released until May 2007.

Justin, 24, appears in the upcoming Edison, starring Kevin Spacey and Morgan Freeman, and Alpha Dog, starring Bruce Willis.

Source: Press Release