Miley Cyrus reportedly feels "threatened" by Jennifer Lawrence's successful career.

Miley achieved worldwide fame on TV show Hannah Montana and has gone on to appear in a host of movies. However, the 19-year-old is apparently worried that other stars could be overtaking her. Jennifer has been thrust into the public spotlight since landing the lead role of Katniss in The Hunger Games franchise.

"Miley feels threatened by Jennifer's career and confidence," a source told British magazine Grazia.

The Hunger Games also stars Miley's fianc Liam Hemsworth, who plays one of Katniss' love interests.

Miley has been regularly seen visiting the gym and it has been claimed she is eager to remain in shape so she can continue building on her acting and music success.

"Jennifer seems to have replaced Miley as Hollywood's It girl. And now Miley seems terrified she'll replace her as Liam's girlfriend too. That's when she started working out so much and the weight dropped off," the insider added.

"Miley's had to grow up fast and I guess she's worried her success could all end tomorrow. She's barely sleeping it's very sad."