Danii Minogue promised to take a good care of her sister, Kylie Minogue, while Olivier Martinez, Kylie's fiancee, will be in Romania to shoot for a movie.

Danii, Kylie's little sister, will move for two weeks in the singer's house, to help her recovering from breast cancer.

According to close friends, Kylie was devastated by Olivier's departure, because she considered him "her rock" and now she thinks she will have to battle the cancer alone.

"Olivier is her rock and she has been dreading him going away," a friend told The People. "He will be gone for months and everyone is really worried about her."

After she was diagnosed with breast cancer earlier this year, Kylie suffered two operations in Melbourne, Australia and intensive chemotherapy and radiation treatment in Paris.