Kenneth McNeill, 52, was found dead in a third-floor flat on Dumbarton Road in the Scotstoun area of Glasgow at around 1am yesterday.
Detectives said the victim was the ''intended target'' of the attack and they are following a definite line of inquiry.
Paramedics were called but Mr McNeill died at the scene.
Speaking yesterday, Detective Chief Inspector Jim Smith said: "Although a post-mortem examination will be carried out, we are treating his death as murder.
''At this time, it is believed that a man arrived at the flat around 0050 hours, forced his way into the house and assaulted the victim, who was not the householder. It is not clear what the motive was but it was not a random act. It would appear that the victim was the intended target, however at this time it is unclear why.
''I would appeal to anyone who was at or near the flats late on Wednesday evening into Thursday morning, and heard a disturbance or saw the suspect either arriving or leaving the scene, to get in touch.
The suspect is described as a white man, 5ft 6in to 5ft 7in, medium to skinny build with short fair hair. He was wearing a light-coloured top. His age is not specified.
Area Commander Chief Inspector Mark Sutherland said: ''I would like to reassure members of the public, particularly those who live in the area of the flats, that everything is being done to trace the person responsible.
''I am aware that local residents will be shocked and alarmed by this incident, however extra patrols will be in the area and I would urge anyone who has concerns to speak to the officers.''