Gwyneth Paltrow had to undergo an emergency grooming session before wearing her racy outfit at the 'Iron Man 3' premiere in Los Angeles.

The 40-year-old actress made jaws drop on the red carpet on Wednesday night (24.04.13) in her revealing Antonio Beradi dress, which showed she wasn't wearing any underwear, but she admits she had to reach for a last minute razor after realising knickers weren't an option with the garment at the last minute.

Speaking on an episode of the 'The Ellen Degeneres Show' to air today (26.04.13), Gwyneth - who was named World's Most Beautiful Woman by People magazine this week - said: ''I kind of had a disaster. I was going to a show and I changed there and I knew I couldn't wear underwear. I don't think I can tell this story on TV ... Well, let's just say everyone went scrambling for a razor ... so I went from being the most beautiful to the most humiliated, in one day. I work a 70s vibe. You know what I mean?''

Gwyneth - who has children Apple, eight, and seven-year-old Moses with husband Chris Martin - was shocked to learn of her title by the popular publication and was initially convinced it was a mistake, even seeking therapy to get her head around it.

She added: ''My publicist of like 22 years, Stephen Huvane, sent me an email. And honestly I was like this is a joke. I reread it three times. I was like, 'Oh, he sent this to the wrong client. Like there's no way.' My name wasn't on it. I was like, 'Oh this is not for me and it was actually psychologically interesting because for a minute I really thought that someone was playing a joke on me.' I talked about it with my shrink.''