Officers were called at around 3am on Sunday, 28 October after a member of the public found the 23-year-old in Dundas Street.
He was taken to the Western General Hospital in Edinburgh where he remains in a critical condition.
Police are unsure how the man came to be injured and are appealing for witnesses.
Detectives are keen to trace the occupants of a dark SUV, possibly Nissan Qashqai, which was seen near the Diamonds pub on Main Street around the time the clocks went back.
Two men were also seen in the area around half an hour before the injured man was found.
One wore a black hooded top with the hood up, black knee-length shorts, white trainer socks and black trainers. The other wore a dark zip-up top with a lighter coloured panel on the chest, dark trousers and was carrying a cream-coloured backpack.
Detective Sergeant Kieran Marsh from Dunfermline CID said: “At this time we have not been able to speak with the man to establish how he sustained his injuries and as such, we’ve got to keep an open mind as to all possibilities.
“With that in mind, we would ask anyone who believes they have information relevant to this investigation to contact police immediately.
“We know that an SUV and two male pedestrians were within the area prior to the man being found and all of these individuals are asked to get in touch to assist with our inquiries as they may have useful information that can help us determine what has happened.”
Those with information can contact Dunfermline CID via 101 and quote incident number 3709 of the 28th October.
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