The trouble with being successful and glamorous is, there is always someone younger and more ambitious coming up behind you.

So move over Keira Knightley, for Emma Watson yesterday gave her older competition a run for her money with a dramatic transformation from child star to grown-up starlet.

The 17-year-old Harry Potter actress, Emma Watson has been keen to distance herself from her schoolgirl character.

And judging by the elegant Chanel outfit and slick of siren red lipstick which replaced her school garb, the A-level student is coming of age at a rapid pace.

As she attended an exclusive dinner hosted by fashion designer Karl Lagerfeld, the immaculately-dressed Miss Watson had even perfected the hand on dropped hip which has become Miss Knightley's trademark red carpet pose.

Like Miss Watson, 22-year-old Miss Knightley began her career as a child actress, starring in Bend It Like Beckham when she was aged 17.

Both young women come from respectable, close-knit families. And both have been courted as muses by the fashion label Chanel.

Emma Watson won a reported £500,000 contract to be the face of the perfume Coco Mademoiselle and is set to play Coco Chanel in a film about her life.

But it was her younger rival - who is on the books of model agency Storm - chosen to be an ambassador for Chanel's fashion range, often appearing on the red carpet and as a cover girl in its lavish outfits.

And in a further snub to Miss Knightley, her fellow actress topped her in a magazine poll of Britain's greatest female role models earlier this year.

Yesterday was no exception to her new appeal with Miss Watson - who has been playing Hermione Granger since she was 11 - donning a black silk pleated dress and shimmering sequined jacket.

In a bid to shed her goody two shoes image, the star partied the night away with Kate Moss and Kelly Osbourne.

Kylie Minogue, Natalie Imbruglia and Sean Lennon joined the glamorous party in London's Nobu restaurant.

A fellow guest at a recent charity gala attended by Emma Watson said: 'She is incredibly self-assured and despite following the likes of Elle Macpherson, is not bothered in the slightest. She is a star and knows it.'

Emma Watson, who is the new face of the iconic brand, was also joined at the event by Charlotte Casiraghi, daughter of Princess Caroline of Monaco, actress Thandie Newton, Sophie Ellis Bextor and Natalie Imbruglia.

Models including Claudia Schiffer, Jodie and Jemma Kidd, Erin O'Connor and Agyness Deyn also attended the affair, which was thrown in honour of Lagerfeld.

Emma Watson's glamorous arrival comes just days after she unveiled her grown up new look in the pages of a glossy magazine.

In the fifties inspired shoot, she looked a world away from the most famous schoolgirl on the planet, Hermione Grainger, the heroine of the films based on JK Rowling's novels.

But the 17-year-old is already well aware of the trappings of fame.

“Recently a woman took my arm, looked at me very seriously and said, 'You're quite pretty in real life.' I didn't quite know how to take it.”

Watson, who has earned an estimated £10 million from the five Potter films, says she shuns stylists for red-carpet events.

“Getting someone else to choose things takes the fun out of it,” she said.

When not working she splits her time between her mother's house in Oxford, and her father's in London.

Emma Watson also has a busy social life.

"For the last three weekends I've been at an 18th birthday party," she said.

Watson, who is currently juggling A-levels and driving lessons, will appear on BBC1 during the Christmas season in a new TV film, Ballet Shoes.

The teenager says she related to her character, Pauline Fossil, an orphan.

"She reminds me a lot of when I was younger," she said.

"I was such a drama queen."

When she got the part she said on her website: “I could not let such an amazing project go. I loved Pauline from the start.”

Set in Thirties London, Ballet Shoes is the story of Pauline and her two sisters, who are adopted by an eccentric explorer, played by Richard Griffiths.

Emma Watson took ballet lessons and dyed her hair whiteblonde for the film, which will be screened on 28 December.

Emma Watson was voted Britain's greatest female role model in a magazine poll earlier this year, ahead of Keira Knightley and Kate Moss.

She is due to start filming the sixth Potter film, Harry Potter And The Half-Blood Prince on 18 December.