A man is fighting for his life following a crash on the Monash Freeway in Mulgrave overnight.
Police have been told two cars were seen travelling city bound on the Monash and appeared to be racing; weaving and changing lanes, when the crash occurred on Monday 28 December about 10.45pm.
The car appeared to lose control before it crashed into the Springvale Road overpass and rolled.
The other vehicle, which was seen speeding alongside the crashed car between Wellington and Springvale roads prior to the collision, didn't stop and fled the scene.
The driver was trapped for some time before he was extricated from the vehicle and taken to hospital by road ambulance in a life-threatening condition.
His male passenger was also taken to hospital with suspected non-life-threatening injuries.
Major Collision Investigation Unit detectives are on scene and have cordoned off the freeway, between Springvale and Ferntree Gully roads, while they process the scene.
All traffic is being diverted off the Monash inbound at Springvale Road and it is expected the diversions will be in place until morning.
Detectives are appealing for the driver of the other car, which is believed to be a white sedan, to come forward.
They are also appealing for any witnesses or motorists with information or dash cam vision, that may have seen the cars racing about 6km prior to the collision near the Eastlink overpass in Dandenong North, to please call Crime Stoppers.
Anyone with information is urged to call Crime Stoppers on 1800 333 000 or can submit a confidential report at www.crimestoppersvic.com.au.
