Rihanna parties with Cara Delevingne at The Box after River Island show

Rihanna ended her night with a cut knee after crazed fan threw a plastic bottle at her

She might have shown her debut London Fashion Week River Island collection to rave reviews, but it seems not everyone is a fan of Rihanna.

As the superstar left Soho haunt The Box with new BFF party girl Cara Delevingne, a fan apparently hurled a bottle of Lucozade at her before firing a stream of insults about her on-off boyfriend Chris Brown.

PICS: RIHANNA FOR RIVER ISLAND AT LFW

Caught up in the commotion, the 24-year-old reportedly fell against a shop shutter and grazed her knee.

Donning a LBD teamed with a leather jacket and black sunglasses, the S&M singer looked chic as continued her way through the scrum of photographers and fans, followed closely by girl of the moment Cara.

Dressed in thigh-high boots, teeny-tiny denim shorts and an over-sized hoodie, 20-year-old Cara showed off her signature quirky style that the whole world has gone gaga for.

14 REASONS WE LOVE CARA DELEVINGNE

Keen to carry their night on, the two girls, and model Jourdan Dunn, headed to Rihanna's digs where her close friend Melissa posted images of them relaxing on a sofa and dancing around the kitchen.

PICS: LONDON FASHION WEEK FRONT ROW STARS

Watch: Rihanna for River Island collection review...