Police and paramedics were called to the Nags Head pub in Blackburn Road after a man in his 20s was found unconscious at 12.20am this morning (Sunday, October 24).
Medics discovered that the man had suffered a serious head injury and a broken jaw after being punched in the face.
He was taken to hospital by ambulance where he remains today, but police say his injuries are not life-threatening.
Lancashire Police said an investigation has been launched and anybody with information is asked to to get in touch.
The force said it also wants to speak to the man pictured in the CCTV image and are asking anybody who recognises him, or knows who he may be, to contact them.
DS Peter Davies, of Hyndburn Police, said: "This was a nasty incident which left a man unconscious and with a head injury and a broken jaw.
"Thankfully he is now in hospital receiving treatment and his injuries are not thought to be life-threatening.
"Enquiries are very much underway to establish what happened and we would like to identify the man in the CCTV image as part of those enquiries.
"If you know him, or recognise him, please let us know straight away.
"We would also like to speak to anybody who was in the pub and saw the incident, or who has any other information that could help with our enquiries."
Anybody with information should call 101, quoting log 0040 of October 24.