A man is fighting for life following a crash on Bacchus Marsh Road in Balliang on Thursday morning.
It is believed a Hyundai sedan collided with a Suzuki hatchback just north of the You Yangs around 9am.
The driver of the hatchback, a 32-year-old Tarneit man, was flown to the Alfred Hospital with life-threatening injuries.
The driver of the sedan, a 45-year-old Strathtulloh woman, was taken to Geelong Hospital by road with minor injuries.
The exact cause of the collision is yet to be determined and investigations remain ongoing.
Anyone who witnessed the collision, has dashcam footage or information is urged to contact Crime Stoppers on 1800 333 000