A man is critically ill in hospital with head injuries after an altercation with a group of youths.
The incident happened at about 4.45pm on Wednesday, in King Street, in the city centre, when a 44-year-old white man became involved in an altercation with one of a number of black youths, said police.
The man, who was walking his Rottweiler dog, fell to the ground and suffered a head injury.
He is in Queen's Medical Centre, in Nottingham, in a critical condition.
Police arrested a 19-year-old man on Friday in connection with the investigation. He has been released on bail.
Anyone which information about the incident is asked to call police on 101 or Crimestoppers anonymously on 0800 555111.
