A 31-year-old man was taken to hospital with serious injuries after the second collision in one day between a motorcyclist and car in London Road, Mitcham.
The road was blocked and buses were on diversion until about 3.30pm today after the collision at about 2.30pm near to the junction with Mitcham Park.
The London Ambulance Service were called to reports of a road traffic collision involving a motorcyclist and a car.
The spokesperson said they treated a 31-year-od man for pelvic injuries and took him to the Major Trauma Centre at St George's Hospital in Tooting.
The northbound carriageway of London Road was blocked and buses were on diversion, affecting routes 118, 201 and 280.
It is the same road where a man in his twenties was treated for chest injuries this morning after another collision between a motorcyclist and a car.
A spokesman from the Metropolitan Police confirmed officers were called to reports of a serious collision between a motorcycle and a car.
The spokesman said: "A patient with suspected serious injuries was taken to a local hospital."
Did you see what happened? Contact the news desk on 020 8722 6336 or email Rebecca.middleton@London.newsquest.co.uk.