A Darlington was man taken to Darlington Memorial Hospital with serious injuries after his black Mazda MX5 left the A66 westbound and collided with a tree.
The incident happened at junction with Darlington Road, Long Newton, near Stockton, at 11.30pm on Saturday.
The passenger was also taken to hospital for observation.
Witnesses are asked to call PC Jayson Morris on 01642-326326.
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