Police say two men attacked the 36-year-old Batley man on Warwick Road, leaving him in the street when they fled the scene.
The attack happened late on Thursday night, between 10.15pm and 10.45pm, but police have only now released details.
The victim was taken to Leeds General Infirmary with a serious head injury, where he remained today (Saturday) in a serious condition.
Detective Inspector Seth Robinson of Kirklees CID, said: “We are continuing enquiries into what has been a very serious assault which has left a local man with serious head injuries.
“ I would like to speak with anyone who saw what took place or has any information about the incident.
“We would also like anyone who saw the two suspects running away from Warwick Road onto Town Street, just after the attack."
The first suspect is described as Asian, about 6ft tall of slim to medium build and wearing a dark hooded top.
The second man was 5ft 6ins tall, stocky and wearing a dark coloured hooded top.
Anyone with information is asked to contact Kirklees CID on 101 referencing crime number 13170345427.