Two 18-year-old men were attacked in Shalesmoor, with one taken to hospital with life threatening injuries, at around 10pm on Friday, October 28.
The other suffered minor head injuries, which also needed treatment.
Both men have since been discharged from hospital.
E-fits have been released of two men police believe could hold vital information on the stabbing.
Detective Constable Joanna Glaves, of South Yorkshire Police, said: “We issued a public appeal for information at the time of this incident but have not yet been able to identify those responsible.
“We are treating this incident as a racially aggravated assault and want to trace the two individuals pictured.
“If you were in the area that evening and hold any information about the assault, or recognise these two men, please get in touch.”
Anyone with information should call South Yorkshire Police on 101 or Crimestoppers on 0800 555111.