Friends of Selena Gomez are afraid her friendship with model Cara Delevingne is seriously bad news for the actress and singer, who secretly completed a stint in rehab earlier this year.

Justin Bieber Getting Revenge On Cara Delevingne For Close Relationship With Selena Gomez?

The two, who were seen partying it up together in St. Tropez for Gomez's 22nd birthday at the end of July, have grown increasingly more close, but Delevingne's penchant for partying has those close to the former Disney Channel starlet concerned about the relationship-especially since Gomez and on/off boyfriend Justin Bieber broke up again just a few weeks ago.

"They've got really close, but Selena's pals know Cara has a wild side, and they're desperate to keep Selena sober-she's vulnerable, especially as her on-off romance with Justin Bieber ended a few weeks ago," a source told British Magazine Closer ( via TV 3).

Cara Delevingne & Selena Gomez Party Together In St. Tropez

"Selena is still getting herself back together post-rehab, and friends fear Cara might be a bad influence," the source added.

However, Gomez reportedly maintains that her friendship with Delevingne is nothing to be concerned about, and that she's thoroughly in control of her life.

"Selena insists she's in control. She really likes Cara and her carefree attitude," the source said.

However, those close to the star who are concerned that Delevingne is having a a negative influence on her may have genuine reasons behind their worry. Not only did the 22-year-old get into a fender bender August 3rd (caused allegedly by her being distracted by swarming paparazzi), but In Touch claims she secretly overdosed a while back and has been partying hard and experimenting with numerous drugs since she left rehab in January.

The magazine, which made the reported story the cover for their most recent issue, claimed that the star was headed back to rehab soon, because she overdosed following excessive partying, as well as drug and drinking binges that have gotten her family seriously worried.