Police are appealing for witnesses following a collision between a car and a motorcycle near Swanmore last month.
Officers are particularly keen to speak to a member of the public who helped the motorcyclist after the crash.
The black Yamaha R6 motorcycle collided with a light blue Nissan Micra on the A32 near Stocks Lane, Corhampton, at about 1pm on August 30.
The rider, 27, suffered serious and potentially life-threatening injuries.
PC Phil Robertson, of Havant Roads Policing Unit, said: “Police are hoping to locate a male member of the public who came to the aid of the rider.
“The man, known as Max, spoke to the rider’s girlfriend on the telephone and may hold vital evidence relating to the accident.
“We would also like to hear from any other person who may have witnessed the incident.”
Anyone with information is asked to contact PC Robertson on 101 quoting 44160326229, or call Crimestoppers anonymously on 0800 555 111.