Police said the driver came across the man, who was lying in the middle of Lygon Street, near Overend Street in Brunswick, shortly after 2.30am.
The man quickly raised the alarm and emergency services attended the scene.
The 24-year-old North Melbourne man was taken to hospital, where he remains in a serious but stable condition.
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Detectives would like to speak to a nurse who they believe tended to the man and left the scene before police were able to establish her details.
Police are appealing for witnesses and or motorists with dashcam to come forward.
