The 29-year-old victim was walking with two friends in Peel Glen Road in the Drumchapel are of Glasgow at around 1.30am today when he was assaulted by a group of men.
The man suffered serious head injuries and remains in hospital. His friends were not hurt in the attack.
Police said there is no description of the men involved at the moment but it is believed they made off in a silver car towards Kinfauns Drive, Drumchapel.
Officers are carrying out door to door inquiries in the area and checking CCTV.
A party was being held in the the street where the attack took place and police want to hear from any potential witnesses.
Detective Sergeant Andy Gibson said: "The injured man sustained serious head injuries during the attack and is in a serious condition in hospital. His friends were not injured and we are trying to piece together the circumstances surrounding the attack - was he the intended target for example?
"Our inquiries are at an early stage and I would appeal to anyone who was in the area to contact Drumchapel CID on the non emergency number 101.
"The weather was good on Friday night into Saturday morning and although the area is residential, it is very possible people were still out and about or up at this time.
"We know there was a party in the street and whilst there is no indication that any of the people involved in the assault were there, revellers may have seen or heard something that will help us with our inquiries."