CHARLIZE THERON fears she’ll lose her fat Dior deal if rival Scarlett Johansson continues her love affair with all things French.

Sources say reps for the fashion giant have told the Oscar-winning “Monster” star – who reportedly banks $5 million a year as the face for Dior’s signature fragrance line J’Adore – that she “needs to be more French.”

Meanwhile, 28-year-old Scarlett is fast becoming the A-list darling of Paris thanks to her French “Vanity Fair” cover and romance with Frenchman Romain Dauriac, a former art journalist.

“Scarlett adores Paris and has spent months there with Romain,” a source told The ENQUIRER.

“Besides that, the French have really responded to her photos in ‘Vanity Fair,’ especially one shot that’s reminiscent of Brigitte Bardot.”

That’s got Los Angeles-based Charlize, 37, on edge, said the source.

“Charlize has done really well for Dior, but the company has to stay fresh,” explained the source. “They’re worried that Charlize comes across as too aloof and are looking at Scarlett as a possible replacement.”

So Charlize is now scrambling to keep the lucrative gig. “She’s taking French lessons twice a week and listens to French tapes in the car to become more fluent,” revealed the source.

“She also dines with Dior execs regularly to brainstorm ideas about how she can be more appealing to their French customer base.

“But Charlize feels that no matter what she does, Scarlett is a real threat. She knows that if she wants to keep her Dior deal, she has to up her game.”