Greensborough Highway Patrol officers are appealing for witnesses following a three-car collision at Thomastown on Thursday.
The first collision occurred on the Metropolitan Ring Road, near the Dalton Road entry ramp, when a grey utility with an aluminium tray collided with the front right side of a silver Mitsubishi about 3pm.
Both vehicles were travelling east, towards Greensborough when the collision occurred.
The driver of the Mitsubishi, a 28-year-old Preston man, stopped in the right lane of the freeway, resulting in three other vehicles also having to brake and come to a stop.
The last vehicle, a white Volkswagen SUV, was unable to stop in time and collided into the vehicle in front of him, a black Great wall utility
The driver of the Great Wall utility, a 26-year-old Greensborough man was conveyed to hospital with serious injuries.
Investigators are trying to identify the driver of the grey utility who failed to stop at the scene.
Anyone who may have seen the collision or who has dashcam footage is urged to contact Crime Stoppers on 18000 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au.