A man was taken to hospital after he was reportedly slashed in Dundee city centre.
The man was left with a “serious” injury to the back of his head following the incident at 1am on Sunday.
He was said to have been attacked on either St Andrews Street or St Andrews Lane at around 12.50am, while the area was busy with night-time revellers.
Officers are now hunting for the culprit and have launched an appeal to find the person responsible.
A spokesman said: “The man sustained a head injury in the incident, which is being investigated as an assault.
“He required treatment at Ninewells Hospital but was later discharged.” Police said a number of witnesses had already been spoken to and city centre CCTV was also being reviewed.
A witness, who didn’t want to be named, said: “It looked as if he was slashed on the back of his head although I couldn’t be sure.”
The police spokesman added: “We would still like to speak with anyone who was in the area around this time as they may have information that could assist us.
“The area was very busy with people enjoying the city nightlife.
“We would like to trace a man described as being in his 40s and who was wearing a long-sleeved white shirt. He was in the company of a woman.
“Anyone with information can call 101 or speak with any police officer.
“Also, information can be given anonymously through Crimestoppers on 0800 555 111. Our reference is CR/23027/18.”
Police returned to the area at lunchtime today to review further CCTV footage from local businesses.