A man is in hospital with a serious head injury after his car flipped over the central reservation barrier on the Sheffield Parkway.
The motorist was driving into Sheffield city centre when his car struck the barrier and flipped over onto the opposite side of the carriageway.
South Yorkshire Police said no other vehicles were involved.
An investigation into the circumstances surrounding the crash is underway.
A police spokesman said: "This happened in the early hours of this morning on the Parkway.
"The vehicle was actually travelling into city when it hit the central barrier and flipped over onto the opposite carriageway.
"Luckily no other vehicles were involved but it could have been so much worse.
"The driver ended up in hospital with a serious head injury.
"Enquiries are now on going to establish the cause."