The 31-year-old victim was walking on Queen Street at around 2.30am on Monday October 15 when he was involved in a verbal altercation with a man and woman.
The woman then handed a brick to the man, who ran towards the victim, throwing the brick in his face. The pair then made off from the scene.
The man suffered a broken eye socket and broken cheekbone. He was later taken to the Royal Lancaster Infirmary for treatment.
Following CCTV enquiries, police wish to identify the two people in connection with the offence.
Det Con Lucy Illingworth of Lancaster CID said: “This was a shocking and brutal assault where the victim has had a brick thrown in his face at close range.
“We want to identify these individuals and believe someone will know who they are.
“If you can help, please contact police immediately.”
Anyone with information can contact police on 101 or email [email protected] quoting log 1380 of October 16.
Alternatively contact independent charity Crimestoppers on 0800 555 111.