A judge at Cardiff Crown Court has warned a pub reveller he is facing jail for killing a man with a freak punch.
False aneurisms are extremely rare
Andrew Ridings, 28, admitted striking Robert Jones at the Castle pub in Tredegar, Blaenau Gwent.
The punch, the court head, caused Mr Jones to have a fatal brain haemorrhage.
The court heard Mr Jones, 52, died of a rare false aneurism - a condition that has only been recorded 15 times.
Prosecutor Thomas Teague QC said: "This is an extremely unusual condition which is usually associated with a stab or bullet wound. It's extremely rare for such an injury to occur in a case with no penetrative injury.
"If he had anticipated the punch and braced himself for the impact it would have been less likely to cause the kind of head movement to produce the aneurism."
Mr Jones died in hospital 10 days after the fight in the Castle pub at Tredegar in Blaenau Gwent.
Ridings, who was from the town, admitted manslaughter and was released on bail to await sentence later this month.
But Judge John Griffith Williams QC warned him: "The only sentence for this offence is one of imprisonment."
Detective Inspector Tony Maher said after the case: "A false aneurism is extremely rare. There are only 15 cases recorded."