An argument between and man and wife resulted in the husband being stabbed by a screwdriver.
Mangal Arman was arguing with his partner when Mohammed Iylas intervened, Bristol Crown Court heard.
In a fracas which followed Arman stabbed Mr Iylas with the tool.
Arman, 26, of Brantley Road in Birmingham, pleaded guilty to unlawful wounding and having an offensive weapon on Oxford Place, Easton, on January 20 last year.
Judge James Patrick adjourned the case until June 25 for a hearing to examine Arman's basis of plea.
Arman was bailed on condition he live at his address.
Mark Worsley, prosecuting via video link, told the court the guilty pleas were accepted but not on the basis given by Arman.
Lucinda Wilmott-Lascelles, defending via video link, said it was her client's case that he was arguing with his wife before two men started fighting at the scene.
Arman said one of them, Mr Iylas, then approached him and backed him into a corner.
Arman claimed he took the screwdriver out of his pocket and told the man he didn't want to fight before lashing out with it.
He said it was Mr Iylas, not he, who was the initial aggressor.
But he accepted he went above and beyond what could be considered as self-defence by producing the screwdriver and using it in the way he did.
The hearing on June 25 will involve an estimated one-day examination of Arman's basis of plea with the calling of witnesses to events.
