Police were called to the intersection of the Stuart Highway and Woolner Road in Darwin on Friday morning after reports of a car hitting a bike.
On arrival, the cyclist was being helped by paramedics and the driver of the ute was nowhere to be found, with witnesses saying two people were seen running from the crash.
NT Police Detective Senior Sergeant Brendan Lindner said alcohol was likely involved.
"The probability of this involving alcohol is quite high," he said on Friday morning.
"The utility driver has driven into the back of the cyclist ... post that incident, the utility has left the road, clipped a pole and then rolled and landed on its roof."
The cyclist was taken to hospital in a critical condition, which has since been downgraded to serious condition.
Det Sgt Lindner said he was looking at CCTV to find an adult male and female pair seen "running from the area".
"We can't confirm yet whether they were in the car," he said.
The driver of the vehicle has not reported the incident and police are searching for the registered owner.
Det Sgt Lindner said the driver would be facing a "serious" hit-and-run charge.
"This is becoming an all too common occurrence in the Northern Territory ... motorists are becoming involved in crashes and then fleeing the scene," he said.
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