Police are investigating a serious crash at Gawler overnight.
Police were called to the scene at Top Gawler Road about 10:50pm, after a Holden Commodore sedan failed to negotiate a right-hand bend in the road.
The car then ran off the verge and crashed head-on into a tree.
The man driving was flown to the Royal Hobart Hospital in a serious condition.
He was the sole occupant of the car and was wearing a seatbelt.
The cause of the crash remains under investigation.