A man was taken to hospitsal after being struck several times with a hammer and kicked in the head before losing consciousness in his own home.
The aggravated burglary happened in the Belvoir area of east Belfast.
Police have described his injuries as "potentially life-changing".
Detectives in Musgrave Street are appealing for information following the report of an aggravated burglary in the Belvoir Street area of Belfast on January 1.
Sergeant McPhillips said: “Two men came to the house in Belvoir Street between 1.30 am and 2.30 am on Tuesday and when the occupier of the property opened the door, they forced their way in.
“The man was then struck several times around the face with a baton/hammer.
“When he fell to the ground he was kicked in the head and torso before losing consciousness.
“The victim was subsequently taken to hospital for treatment.”
He said this was “a particularly vicious incident which has left one man in hospital with what could potentially be life-changing injuries”.
“I would appeal to anyone who was in the area at the time and saw two men acting suspiciously to get in touch with detectives as soon as possible on the non-emergency number 101, quoting reference number 287 of 03/01/19.”
“Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.”