Cameron Diaz set for Expecting

Cameron Diaz is in talks to join the cast of 'What to Expect When You're Expecting'.

The 'Bad Teacher' star has reportedly been lined up to take on a role of a weight-loss instructor who hosts a fitness TV show in the romantic comedy based on the bestselling guidebook for new parents by Heidi Murkhoff.

The original screenplay by Heather Hach was set to feature seven sets of expectant parents but has now been cut down to five by 'Whip It's Shauna Cross, while 'Nanny McPhee' director Kirk Jones will direct.

Mike Medavoy, Arnie Messer and David Thwaites will produce the movie for Lionsgate.

It was recently announced that Cameron, 38, will star in 'Gambit' alongside Oscar winner Colin Firth.

The movie - which is a remake of the 1966 film, starring Sir Michael Caine and Shirley MacLaine - will be directed by Michael Hoffman and produced by Mike Lobell with shooting set to start in London in May.

Colin will play a London art curator who plans to con a wealthy collector into buying a phony Monet painting and enlists a Texas cowgirl, played by Cameron, to pose as a woman whose grandfather liberated the painting at the end of World War II.