A man was stabbed in both testicles during an "unprovoked" attack in a bar in Chelsea, west London.
Police have appealed for information about the attack at the Eclipse Bar in Walton Street between 20 and 21 August.
The 31-year-old victim, of Isleworth, was with friends when a man punched him, leading to a scuffle. The victim, who was taken to hospital, was stabbed once in both testicles.
Officers released a CCTV image of a man who they believe punched the victim.
A number of people tried to stop the fight. The attacker fled in the direction of Brompton Road when the victim was knocked to the ground, police said.
Following the assault the 31-year-old felt a sharp pain and noticed he was bleeding. Staff at the bar tried to stop the bleeding.
The victim underwent surgery and was released from hospital about a week after the attack.
Det Cons Mike Jones said: "The victim and the other people involved in the incident in the club do not know the suspect and no one has come forward to identify him.
"This was a nasty attack which we believe to be unprovoked. We need anyone who knows this man to contact police."