A top US skin doctor has given Renee Zellweger the thumbs up to play Janis Joplin in a new biopic - because the actress will be able to appreciate the hell the rock legend went through with adult acne.

DR VAIL REESE, who doesn't treat Zellweger, insists those who suffer from post-teenage acne have tremendous feelings of insecurity.

And the San Francisco, California skin expert thinks the BRIDGET JONES'S DIARY star will be able to get to the core of Joplin's character because both of them face(d) a daily battle with blemishes.

Reese says, "Having adult acne is more than just a cosmetic issue. It erodes people's confidence and lowers self-esteem.

"Since Renee Zellweger has talked about having this condition, she may better connect with whatever emotional demons drove Janis Joplin."