A dad killed his son in a row after a 12-hour drinking marathon celebrating Wales beating England in this year's Six Nations rugby championship.
A court heard Neil Davies grabbed a kitchen knife in his flat and slashed 24-year-old Joshua's jugular vein .
A distraught Davies, 53, then called 999 saying: "I just stabbed my son, please help."
A neighbour also overheard Davies crying: "He's dying, what have I done?"
The pair had first clashed at a British Legion club in Rumney, Cardiff, and Davies said that his son, a boxer, had given him a black eye.
David Aubrey, defending, told Cardiff crown court: "He will have to live with this for the rest of his life."
Davies got five years after admitting manslaughter.
Both men were almost three times the drink-drive limit.
The court heard that Davies told police later: "He is my boy - he's a boxer and gave me a black eye."
The pair had been drinking for almost 12 hours at a pub and a British Legion club in Rumney, Cardiff.
They had been watching the final day of last season's Six Nations competition in March when Wales beat England by a record score of 30-3 .
Cardiff Crown Court heard CCTV footage at the club showed the couple pushing each other and arguing shortly before they left just after midnight to return to their nearby home.
Prosecutor Peter Davies said: "There had been friction between the two in the hours before this happened.
"There had been a stand-up argument at the British Legion Club and it continued afterwards but only Neil Davies knows what happened in the flat."