Barry Gavin, 20, confronted Damian Muir with a knife as he made his way home in July.
Gavin demanded the time and when the 34-year-old replied: "How the f*** do I know?" stabbed him eight times with such force the knife snapped and became lodged in his pelvis, the High Court in Glasgow was told.
Gavin, who has two previous convictions for carrying knifes, told detectives: "I bumped into some guy, I've no idea who he was. I just lost it with him.
"The guy was in the wrong place at the wrong time."
He added: "I sometimes take my anger out on other people."
Yesterday Gavin, of Greenock, admitted murdering Mr Muir, an IBM call centre worker, of Inverkip, on 14 July in Greenock.
The prosecutor, John Martin told the judge, Lord Brodie, Mr Muir was walking home from a function in a local bowling club for his amateur football team.
The court heard how Gavin was angry because his partner had left with friends to buy cigarettes at a garage and gone on to a party, leaving him with their ten-month-old baby.
He left the infant at home to go out and find her, meeting Mr Muir on the way.
Mr Martin said that a passing taxi driver saw the victim on the ground with Gavin thumping into him with "ferocious, vicious punches". Knife wounds to the lung and heart were fatal and
he died just before an ambulance got him to Inverclyde Royal Hospital.
Mr Muir was a keen sportsman who played badminton, golf and for the local football team, Broomhill Amateurs.
His father John, 68, said: "We are coping. My wife feels the loss sorely. Damian was always a pet boy to his mother, the youngest boy. We're hurting."
Gavin will be sentenced next month.