Lancashire police are appealing for information after a woman was assaulted outside a pub in Chorley.
Police were called around 2.40am on November 19 following reports of an incident close to the Flat Iron pub in Cleveland Street.
A man had been drinking in the pub when he went outside for a cigarette.
When he attempted to re-enter the pub he was refused entry inside and became abusive, punching a female door staff member.
The woman, aged 30, fell to the floor, seriously injuring her right knee, with the attacker making off from the scene.
Following extensive enquiries police would like to speak to this man, pictured, in connection with their investigation.
PC Mark Price, of Chorley Police, said: “This was a nasty, unprovoked assault on a woman just doing her job.
“It was particularly cowardly and has left the woman with serious injuries to her right knee, sustained as she has lost balance.
“Following investigation we would like to speak to this man. We believe someone must know who he is and would encourage anyone with information to contact us.”
Anyone who recognises the man or can assist with our enquiries is urged to contact police on 101 quoting crime reference SC1708981.
Alternatively independent charity Crimestoppers on 0800 555111 or online at crimestoppers-uk.org.