The victim was approached by two men at around 6.30am on Wednesday, September 27 whilst he was walking along Penns Road in Heeley.
One of the men is said to have put a knife to the 33-year-old man's throat before making demands for cash.
Detective Constable Ryan Griffiths, the investigating officer, said: “The two men then led the victim to a grassy area nearby on Derby Street where they searched his pockets and bag before stealing his coat, cash, iPhone, games console and two bankcards.
“They demanded the pin code for his bankcard before leaving towards Gleadless Road, where one of the men went into the Co-Op store.
“This was a nasty, unprovoked attack and I’m hoping that someone will recognise the man in the footage. We believe he could hold important information about what happened.”
Police have released CCTV footage of a man they would like to identify.
If you know who the man pictured is, please call 101 quoting incident number 132 of 27 September 2017.