'I'm just in shock': Rihanna surprises fan in the changing room as she's trying on clothes from her new River Island collection

PUBLISHED: 00:11, 10 March 2013 | UPDATED: 00:13, 10 March 2013

While many Rihanna fans have been eagerly awaiting the arrival of her collection for River Island, one lucky girl got a bit more than she bargained for when she headed to the launch to check out the clothes last week.

While trying on one of the new dresses, the shopper was interrupted by a knock on the changing room door by none other than the superstar herself.

Clearly shocked by coming face-to-face with her idol, the young girl seemed in a daze as she hugged the singer before describing it as 'the best start to 2013.'

Surprise! Rihanna shocks a stunned fan who is trying on a dress from her new River Island collection in the changing room

The fan, who had won a competition to be one of the first to see the collection, was the first person to actually try on one of the pieces designed my Rihanna.

The day before the collection was made available to the public, a few lucky winners were allowed in to the brand's flagship store.

And one fan, named Maneira, was clearly unaware that she'd run into the designer herself, making a beeline for the changing room holding a black dress.

Sneaking up: The Diamonds star makes her way into the changing room ahead of the surprise

Stealth like: Rihanna waits quietly outside the changing room door, telling the camera to star back as it's a girl who's changing

Initial shock: The young fan puts her hands over her face as Rihanna pokes her head inside the cubicle

Rihanna tip-toed up to the changing room with a camera in tow, and waited patiently outside, mouthing to the crew that she was a girl.

And when the shopper stepped out in the dress to show a friend, Rihanna poked her head in, giving her the surprise of her life.

'Oh my God, oh my God,' she kept saying over and over again when she realised who it was, putting her hand over her mouth.

Over the moon: The shopper seems overjoyed to see her idol close-up

Hug it out: The down-to-earth pop star grabs her fans for a huge hug, pulling her in close

'I'm in shock': The fan admits that she's stunned by the fact that Rihanna was waiting outside the door

'Congratulations - how do you feel to be the first person in the world, except for me, to wear one of these dresses?' asked the Rude Girl singer.

'This is amazing. It's beautiful and you're beautiful as well,' said the stunned fan.' I'm just in shock. Is this the real Rihanna?'

'You're the first person to try on my clothes and the good new is - you get to keep the dress,' continued the pop star.

'This is like the best start to 2013, I can't wait for the rest of the year,' added Maneira. 'It was an amazing experience.'

Rihanna kicked off her 27-city Diamonds world tour on Friday night in New York City, wearing a number of revealing outfits, designed by Adam Selman, who collaborated with the singer on her River Island collection.