Renee Zellweger's new face

Renee Zellweger before and after. Photo / Getty

She's well known for transforming her appearance for movie roles.

But off-screen Renee Zellweger, 45, displayed an astonishingly different look at ELLE's 21st annual Women In Hollywood Awards at the Four Seasons Hotel in California on Monday.

The Jerry Maguire actress looked almost unrecognisable with her super line-free forehead, altered brow and suspiciously puffy face, although she has never admitted to getting surgery.

She wore her blonde hair in a wispy side-parting, and kept her makeup natural, opting for a light touch of mascara and a slick of pink lipgloss.

Her choice of dress was a winning look, a black knee-length frock with sweetheart neckline and a sheer embroidered back and sleeves.

She teamed it with gold pointed pumps by Christian Louboutin and carried a matching clutch.

Dr Alex Karidis of London's Karaidis Clinic , who has never treated Renee, told MailOnline he believes Renee may have had an upper eye lift.

He reasons: "The distance between the brow and her eye is much smaller than before."

According to Dr Karidis, the 45-year-old's brows don't appear to be higher than before, suggesting she hasn't had a brow lift.

Renee Zellweger. Photo / Getty Images

Karidis says her flawless forehead could be down to the use of Botox.

He said: "Her forehead is smooth - you would expect more expressive wrinkles when she smiles which indicates a possible small dose of Botox between the eyelid and eye."

Last year the blonde beauty spoke to The Express about staying healthy and explained:

"I have a lifestyle that involves keeping my sanity by going to the gym."

Talking about her fluctuating weight for her role in the Bridget Jones' Diary franchise, she is fed up over constant speculation about her appearance.

What the experts say

Plastic and Cosmetic Surgeon Dr Alex Karidis from London's Karaidis Clinic told MailOnline he believes Renee may have had an upper eye lift as 'the distance between the brow and her eye is much smaller than before.'

Alex also explained there is more of her eyelid showing and her eyes look much bigger, however her brows are not higher which suggests she hasn't had a brow lift. 'Her forehead is smooth - you would expect more expressive wrinkles when she smiles which indicates a possible small dose of Botox between eyelid and eye,'

Dr Karidis told. He also suggested she could have had 'non-surgical treatments such as ultrasound therapy to firm the skin and medical grade facial to get rid of dead skin cells."

- Daily Mail