Detectives are appealing for witnesses and dash cam footage following a serious collision in Sutton.
Police were called at approximately 22:15hrs on Friday, 16 October to reports of a car in collision with a pedestrian on London Road, near the junction with Garth Road in Cheam.
Officers and the London Ambulance Service attended.
The 21-year-old pedestrian was taken to a south London hospital, where she remains in a critical condition.
The driver failed to stop at the scene but was arrested a short time later on suspicion of drink driving. He was taken to a police station for questioning and remains in custody at this time.
Any witnesses or anyone with any information is asked to call the Serious Collision Investigation Unit on 0208543 5157, or call 101/ tweet @MetCC ref CAD 8295/16OCT20.