Rihanna says she will never end up in rehab because she thrives on pressure.

The singing superstar - who shot to fame with 'Pon De Replay' in 2005after Jay-Z discovered her when she was just 16 - has taken the world by storm, but she admits she won't let the pressure get to her and end up at a treatment facility.

Speaking about going into rehab she told Mondanite magazine: "That will never happen to me.  I refuse to crack under pressure - in fact I thrive on it.  So when I read about Britney Spears and Amy Winehouse who have suffered under it, it's sad.  It is easy to criticise them but it happens.  You just have to stay focused and keep your feet on the ground."

The 23-year-old star also says she stays grounded by phoning her best friend.

She said: "Staying down to earth in this industry in general is really not easy, but I am strong and when I feel lost or depressed on the road, I call my best friends Melissa.  When I see people turning to drugs and alcohol, then that's when I call Melissa.  She helps me get through things."

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