A 21-year-old man suffered a “horrendous” neck injury after being attacked in Dunfermline town centre.
He was assaulted in Monastery Street between 4am and 5am on New Year’s Day.
The severity of the man’s injury suggests a weapon was used, said police.
Detective Sergeant Christopher Dow of Dunfermline CID said: “This has been a particularly frightening experience for the victim and he has suffered a horrendous injury.
“The nature of the injury would suggest that the individual responsible has used a weapon of some description and it is through sheer fortune that the consequences have not been even more severe.”
Officers are appealing for anyone who witnessed the incident or has CCTV footage which could help the investigation to get in touch.
“If you were in the area early on Tuesday morning and have seen any persons or vehicles that appeared unusual, or if you have any CCTV which may assist in our inquiries, please contact police,” said Mr Dow.
“Due to it being Hogmanay there have been a number of social events in the area, so if you have been using your phone to capture footage or photos and have images of a man matching the description, I would urge you to please call us.”
The attacker was described by police as an Asian man in his 20s who was around 5ft 9in to 6ft tall and of medium build. He had dark hair, a trimmed dark beard and was wearing a grey or dark coloured tracksuit.
Anyone with information is asked to call police on 101, quoting incident 2038 of January 1, or contact the charity Crimestoppers anonymously on 0800 555 111.
