Olivia Rodrigo, Lily Allen reunite for surprise duet

Olivia Rodrigo is currently on the UK leg of her GUTS tour.

On Friday, the Vampire hitmaker welcomed Lily Allen to the stage during her performance at the London O2 Arena.

Previously, the duo sang Allen's F*** You in response to the US Supreme Court's decision to overturn Roe v Wade.

Dressed to impress, Rodrigo wore a black bra top and hot pants co-ord with a sparkly overlay and fishnet tights, while Allen flashed her abs in a white tank top and black Miu Miu mini skirt.

The duo's chemistry was palpable as they sang, "At first when I see you cry it makes me smile."

Allen also expressed her gratitude on Instagram, posting, "been a while since i’ve sang at the O2. what a lovely crowd, what a lovely crew. Thank you @oliviarodrigo."