Police are trying to trace a man who had a concrete slab smashed over his head in an early morning assault in the city centre.
Shortly after 4.35am on Wednesday 16 July 2014, Manchester City CCTV operators captured an incident on Bloom Street.
The footage shows two men embracing briefly before the offender removes a slab of concrete that was concealed at the back of his trousers.
He then lifts the weapon above his head when the victimâ€™s back is turned and smashes it over his head.
The incident was reported to police by CCTV operators and a man was arrested on suspicion of assault nearby.
He has been released on bail until 2 September 2014, pending further enquiries.
The victim has not been identified or located, having left the area in a taxi following the incident. He was taken to the junction of Anson Road and Dennison Road by the taxi driver.
Detectives are now appealing for the victim to contact them or the public to help identify him or the two people who appear to be with him.
He is described as black, 25 to 30 years, of medium build and was wearing a white t-shirt, black top, jeans and black shoes.
Detective Constable Tom Hornby, said: â€œThe footage clearly shows the offender smashing a concrete slab over the victimâ€™s head with force while his back is turned.
â€œIt was a cowardly and unprovoked assault and we desperately need to identify this man in order to check on his welfare.
â€œWe also need to trace him because at this time we are effectively dealing with a victimless crime, which is clearly not the case.
â€œWe need to take an account of what happened from him and record his injuries so we can properly and thoroughly investigate this matter and bring the offender to justice.
â€œIf you are the person in the CCTV or one of the people he appears to be with or you know who they are, please contact us.â€
Anyone with information is asked to call police on 0161 856 39597 or Crimestoppers, anonymously, onÂ 0800 555 111.