A serious assault on a 20-year-old man in South Lanarkshire is being treated as attempted murder, police have said.
The man was walking with a friend along Dechmont Street, Hamilton, at about 2250 GMT on Wednesday when they passed a group of people.
A man from the group then hit his victim over the back of the head before running off. His friend was uninjured.
The victim is being treated for "life threatening" injuries in hospital.
Police are conducting door-to-door enquiries and are checking CCTV images.
Det Con Brian Scanlan, of Strathclyde Police, said: "There appears to be no motive for this attack and a young man has been left in a critical condition.
"He suffered a very serious head injury as a result of the assault and it's imperative we trace those responsible.
"I would appeal to anyone who may have seen or heard anything to get in touch with us, the area is primarily residential and if you do have any information about the incident or about the group of individuals who were at the location please contact us."