Police are investigating the circumstances surrounding a crash which occurred in Narre Warren on Sunday, 13 January morning.
Officers have been told a Holden sedan was travelling east along Princes Highway about 1am when the driver lost control of the car.
The car rolled and ended up landing on its roof.
The driver of the car, believed to be a man in his 40s, suffered serious injuries and was taken to hospital.
Three other occupants of the car, a teenage boy and two girls, were not seriously injured but were taken to hospital as a precaution.
Police are investigating if speed or racing was a factor in the crash and wish to speak to the occupants of a red hatch which was seen to be driving near the sedan at the time of the incident.
Anyone who witnessed the crash, with further information or with dash cam footage is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au.