A car driver who hit a pedestrian, bundled him into his car, dropped him off at hospital and fled is being sought by police.
The collision happened on Abbeydale Road with the junction of Batt Street at around 9.20pm on Sunday evening.
Witnesses close to the scene claimed they saw a man had been hit and was put into the back of a car before the vehicle drove off.
Officers took witness statements from two taxi drivers before issuing a wider appeal.
Police say they are wanting to speak to the driver of a black Ford Focus car who was travelling away from the city centre after turning off London Road onto Abbeydale Road.
A South Yorkshire Police spokeswoman said: “It is reported that the occupant or occupants of the Focus stopped at the scene, picked up the pedestrian, a 20-year-old man, and placed him in the car.
“The man, who suffered serious injuries to his hands and neck, was then dropped off outside the Hallamshire Hospital and the vehicle is reported to have left the scene.”
The victim’s injuries are said to be serious but not life threatening.
A police cordon was set up on Abbeydale Road with the junction of Batt Street along the entrance of Mount Pleasant Park.
Traffic was diverted along Wolsely Road for around four hours before the road was re-opened after 1am.
A Batt Street resident who didn’t want to be named said: “I got told that a guy got put in a car, I think he got run over.”
Police have issued an appeal for any witnesses to come forward to try and identify the driver.
Anyone with information is being urged contact 101 quoting incident number 1163 of August 16 2015.