Police are appealing for any witnesses to a road traffic collision that occurred at Streatham Hill near to Brixton Bus Garage.
Police were called on Sunday, 2 August at approximately 21:20hrs to reports of a motorcyclist involved in a collision on Streatham Hill SW2.
Officers, the London Ambulance Service (LAS) and London's Air Ambulance Service attended the scene and found a man aged 42 in a critical condition.
He was taken by LAS to a south London hospital where he remains in a serious but stable condition.
It is believed that the motorcyclist clipped a central kerb prior to colliding with a lamp post by a pedestrian crossing.
Anyone with any information is asked to contact the Serious Collision Investigation Unit at Merton on 020 8543 5157.