Police want to speak to anyone who saw a crash in which an off-road bike rider suffered life-threatening head injuries.
The collision happened in Catcliffe at about 4pm yesterday.
South Yorkshire Police said an orange trials-style bike was being ridding along Sheffield Lane. As it turned onto Poplar War it collided with a silver Kia Picanto travelling towards Highfield Spring.
The 22-year-old bike rider suffered life-threatening head injuries and was taken to hospital where he remains in a critical condition.
The 35-year-old driver of the Picanto and 12-year-old passenger suffered minor injuries.
Witnesses should call 101.