A man suffered serious facial injuries in an unprovoked attack in Wakefield city centre.
The 23-year-old was struck from behind after leaving the Havana Nightclub, on Westgate, at around 3am on Sunday, November 23.
The victim was knocked to the floor and then helped into a taxi by members of the public.
He later attended hospital where he was treated for a serious facial injuries before being discharged.
Det Con Fay Wroe, of Wakefield CID, said: “We are appealing for witnesses to this offence and would like to speak with anyone who saw what happened or who knows the suspect.
“The victim cannot describe the suspect, due to being struck from behind. The attack was completely unprovoked and unexpected”
Anyone with information should contact Wakefield CID on 101 or Crimestoppers, anonymously, on 0800 555111.