Balaclava-wearing robbers broke a man's nose after demanding he hand over his wallet and phone in east Northampton.
Northamptonshire Police are appealing for witnesses who may have seen a robbery taking place in Lings Way, Northampton, on Monday, 9 January.
A 26-year-old man was walking in the area between 10pm and 11pm when he was approached by two men who threatened him, demanding money.
The offenders assaulted the victim, breaking his nose, before making off with items including his wallet and mobile phone.
The first offender, who was carrying a flick knife, was white, 6ft and had a deep voice. He was wearing a balaclava, dark tracksuit bottoms, top and trainers.
The second offender was also about 6ft and wearing a balaclava.
It is believed a member of the public may have witnessed the robbery taking place and officers are appealing for that person to make contact with them.
Witnesses or anyone with information about the incident can contact police on 101, or Crimestoppers anonymously on 0800 111 555.