A man was left with a broken leg, nose and eye socket after an attack in a Chesterfield pub.
The 36-year-old was attacked in the Crown and Cushion on Low Pavement in the town centre during a night out with friends.
Derbyshire Police said it was an unprovoked attack and CCTV images have been released of people in the pub at the time who may have witnessed the violence.
A number of customers that night were from Sheffield.
A police spokeswoman said: "A man suffered serious injuries, including a fractured leg, broken eye socket and broken nose during the attack.
"On Saturday, July 22, a 36-year-old man was at the Crown and Cushion, in Low Pavement, with some friends.
"He made his way to the smoking area when he was suddenly the victim of what we believe to be an unprovoked attack.
"The incident happened sometime between 8pm and 9pm.
"People in the pub at the time recall several customers had come from Sheffield that evening.
"The people in these pictures may have witnessed what happened that evening and we would like to speak to them."
Witnesses or anyone with information should call DC Antonia Hill at Derbyshire Police on 101, quoting reference 17000315344.