A punch which may have killed a man from Suffolk could have been thrown in self defence, a court has heard.
Bradley Baker, who was 31 and from Sizewell, died in King's Lynn, Norfolk, after being punched, Norwich Crown Court has been told.
Christopher Noble, 26, of South Wootton, Norfolk, denies manslaughter.
Witness Robin Green told the court he thought Mr Noble was acting in self defence as he had become involved in a fight with two men.
He said he saw the punched man go down "as if a rug was pulled from under his feet... He went straight down".
Earlier the court heard a post-mortem examination carried out by pathologist Dr Nat Cary revealed the cause of death was a severe head injury because of "a blunt force impact causing a skull fracture".
Mr Baker died in the Queen Elizabeth Hospital in King's Lynn the day after the fight.
Mr Noble claims he was punched and returned the blow in self defence.
John Baldwin, 28, from Mansfield, Nottinghamshire, is also on trial charged with affray in connection with the fight.
The case continues.