A drunken thug knocked a man unconscious and broke his jaw in an unprovoked attack on a night out.
Zach Hartgill-Huntley 'came out of nowhere' to hit Andrew Haydon who had been out with friends in Guildhall Walk, Portsmouth.
Prosecutors say Hartgill-Huntley ran up to his victim and punched him because of an earlier row involving their friends in nearby Yates's Bar.
Mr Haydon and his friends Daniel Hayter and Gemma Cammerer left the bar and were heading to Liquid and Envy when the group from Yates's caught up with them.
One of the men punched Mr Hayter while Hartgill-Huntley attacked Mr Haydon, leaving him out cold on the ground
The 22-year-old admitted hitting Mr Haydon, but claims he was worried about his own safety after someone had thrown a box of chips at him.
Hartgill-Huntley told a judge at Portsmouth Crown Court: 'Someone came up behind me quickly. I turned to my left and punched him because I didn't know what he was going to do to me, do you know what I mean?'
Asked by Daniel Sawyer for the prosecution why he had punched Mr Haydon, he said: 'I don't know. I didn't know what was going to happen to me did I?'
Asked why he ran he said: 'Because I didn't want to get nicked, did I?'
Hartgill-Huntley denied he had anything to do with the earlier row and said he had not been in Yates's.
The victim's friend, Miss Cammerer, said Mr Haydon was sitting on a wall when he was attacked.
'Out of nowhere this bloke just ran and just punched Andy in the face, knocking him to the floor unconscious,' she said.
'Andy was sat on the wall because I told him not to get involved in the argument.'
She said Hartgill-Huntley ran off towards Commercial Road while she went to help Mr Haydon, who has no memory of the attack, before he was taken to Queen Alexandra Hospital.
The attack happened at about 1am on Sunday, July 18.
Hartgill-Huntley, of All Saints Road, Buckland, pleaded guilty to assault causing actual bodily harm.
But Judge Ian Pearson has to rule whether Hartgill-Huntley ran up to Mr Haydon and punched him or, as he claims, he hit him out of fear.
The case was adjourned until January 5. The judge will give his ruling and then sentence Hartgill-Huntley.