Knox Highway Patrol officers are investigating a multi-vehicle collision in Scoresby last night which has left a man in a critical condition.
It is believed a Mercedes was travelling inbound on Eastlink just before 7pm when it allegedly collided with the rear of a Kia hatchback, which in turn struck a semi-trailer.
The driver of the Kia, a 57-year-old man from Blackburn South, was taken to hospital with life-threatening injuries.
The Mercedes driver, a 36-year-old Rowville man, sustained minor injuries.
He has been taken to hospital under police guard.
A 58-year-old Seabrook man, who was driving the semi-trailer, was not injured.
The investigation is ongoing.
Police are appealing for anyone who witnessed the incident or who may have dash cam footage to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au