THE claws are out as JENNIFER LAWRENCE’s hunky BF gets ready to play man-hungry KRISTEN STEWART’s love interest in a sizzling new movie.

“American Hustle” star Jennifer is burning up that a sexy film role she turned down was scooped up by Kristen, who’s now going to be making love onscreen with Jennifer’s British beau Nicholas Hoult.

Kristen, 23, shot to stardom in the “Twilight” movie series – and nabbed her ex-boyfriend Robert Pattinson in the process. Now, she’s starring with 24-year-old Nicholas in the upcoming sci-fi romance “Equals,” and that’s put Jennifer on high alert.

“This is making Jennifer uneasy, to say the least,” said a close source. “She doesn’t want to think the worst of Kristen, but her reputation precedes her.”

Kristen started her off-camera romance with her British co-star Pattinson in 2009. But their relationship unraveled in 2012 when the hot-to-trot actress was caught having an affair with another Brit, her married, 20-years-older “Snow White & the Huntsman” director Rupert Sanders – ultimately wrecking his marriage. Now, sources say that Oscar and Golden Globe winner Jennifer is wondering if Kristen is targeting yet another British guy, her lover Nicholas.

“Jen hung out with Kristen at the Toronto Film Festival in 2012, and they got on quite well,” disclosed a friend. “She told Kristen she had read the script for ‘Equals’ and loved it but didn’t feel the part was right for her. Soon after, Nick signed up for the film, and Jen learned that Kristen was suddenly pursuing the role to play his lover.

“It all worked out a little too conveniently for Jennifer not to be suspicious. Considering Kristen’s history with British men, she’s the last person Jennifer wants to see kissing her boyfriend on the set.”

Stewart’s reputation for onset romances includes “Prison Break” star Lane Garrison, who was cast with her in the film “Camp X-Ray.” A friend says she moved Lane – who served almost two years in prison for a 2007 vehicular manslaughter conviction – into her L.A. home during the shoot and they reconnected at the Jan. 17 premiere at the Sundance Film Festival.

The 23-year-old “Hunger Games” beauty is especially worried because her relationship with Nicholas has been troubled.

The pair began dating in 2010 when they were filming “X-Men: First Class” but split in January 2013. They got back together last summer, and Jennifer is keen to get a ring on her finger.

“Although Jennifer is busy with her super-hot career, she’s determined to make time to visit the ‘Equals’ set and keep a watch over Nick,” noted the friend. “She doesn’t want to see her romance sabotaged.”