A man was stabbed twice on Christmas Eve in the middle of Lincoln High Street.
Police are appealing for witnesses following the incident, which was not reported to them until January 2.
The stabbing is reported to have happened outside Iceland and Poundland at around 2am.
Extra patrols are now being carried out in the area.
A Lincolnshire Police spokesperson said: “It is believed that the offender was wearing a white puffer jacket and is not believed to have left a weapon at the scene.
“The victim could not offer a further description of his attacker and has been treated at Lincoln County Hospital.
“His injuries are not life threatening.
“We need to hear from anyone that may have seen the altercation or a person running away.
“Extra patrols are taking place in the area and officers are monitoring CCTV.
“If you have information please call 101, or to report anonymously, call Crimestoppers on 0800 555 111.”