Robbers pulled a man from his car before stealing cash near Adwick railway station.
The 77-year-old victim was driving his car along Adwick Lane, towards the station, when he reported seeing a man lying in the road whilst another man was standing nearby.
Police say they believe the motorist stopped his car and was then pulled from the vehicle by the pair, who are then alleged to have demanded cash before taking £60 and throwing the 77-year-old man to the ground.
Officers believe that the men ran off in the direction of the train station.
The elderly man suffered minor discomfort, however he sustained no injuries from the incident.
The suspects are described as wearing dark clothing, gloves and woollen masks, and to be 6ft and 5ft 4ins tall.
Witnesses call 101 quoting incident number 201 of 19 December 2014. Alternatively, to give information anonymously, call Crimestoppers on 0800 555 111.