Essex Police believe the pair could hold vital information about an attack in Chelmsford in the early hours of Sunday, December 10.
On the morning of the attack two men started talking to a man and woman, who said they were staying in the area and were from Sheffield.
The conversation turned to football and reference was made to Sheffield Wednesday.
It is claimed that the Sheffield man then punched one of the other men in his face, causing him permanent sight loss in one of his eyes.
An Essex Police spokesman said: "We would like to talk to these people in connection with an assault in Chelmsford that left the victim partially losing his sight.
"Two men were walking in Springfield Road at around 1am on Sunday, December 10, when they began talking to a man and a woman.
"During that conversation, the suspects said they were from Sheffield and staying in the area.
"The victims then started talking about football with a particular reference to Sheffield Wednesday.
"The suspect, who has been described as having a northern accent, then asked whether the men knew who he was before punching one of them in the face.
"The victim, aged in his 20s, was taken to hospital and has permanently lost the use of one of his eyes."
"The people we need to talk to were both in the Missoula bar from 11.20pm on Friday, December 9, and 12.45am the following day."
Anyone with information should call Chelmsford CID on 101 quoting crime reference 42/174577/17 or Crimestoppers anonymously on 0800 555 111.