A teenager took a selfie with the caption 'game time' shortly before he killed a neighbour.
Jack McBride was just 17 when he knifed Johnny Winters in the heart during a confrontation in the street in Johnstone.
McBride had earlier called his ex-girlfriend taunting her that she thought he could not "kill" somebody.
He had gone on trial at the High Court in Glasgow charged with murdering 26 year-old Johnny.
But, via his QC Thomas Ross, McBride had his guilty plea to the reduced charge of culpable homicide accepted by prosecutors today.
McBride - now 19 - was remanded in custody pending sentencing next month.
McBride and Johnny had both lived in High Street, Johnstone.
The killer previously suspected Johnny was responsible for the door of his family home being torched in 2019.
McBride then believed Johnny's partner had later made a threat towards his sister.
On the night of the fatal attack, the teenager called his ex-girlfriend ranting about the victim.
This included him stating: "You think I cannot kill someone. You think my bark is bigger than my bite.
"Johnny Winters thinks he is a name. I will be a name."
Both his ex and his mother failed to calm McBride down. He soon left the flat armed with a kitchen knife on April 1, 2020.
The teenager stormed up outside Johnny's flat and yelled at him to come downstairs.
Prosecutor Neil McCulloch told the court: "McBride video recorded this interaction and shared it over Snapchat.
"The Snapchat commences with a screenshot of a text message sent earlier by him to Johnny Winters.
"It is captioned: 'F*** Johnny - tried him once, I'll try him again. Lets hope he does something this time'.
"McBride can be seen in the recording shouting up at the window demanding he come out.
"Johnny Winters can be heard telling him to come up.
"The recording ends with a selfie of McBride captioned 'game time'."
The victim had been at home with his partner as well as his friend Adam Gallagher.
Adam gave evidence and recalled going onto the street seeing McBride and Johnny "squaring up" to each other.
The witness said: "I was saying to Jack to go back to his house and asking what he was doing. I was trying to get him to see sense."
Jurors heard Johnny then eventually struck McBride with the "blunt side" of a hatchet.
The teenager responded by stabbing Johnny once in the chest with the knife before running off.
Adam said: "Johnny had his new jacket on and I saw the material inside of it coming out.
"I asked: 'Did he stab you?'. He said 'no' then his face changed, he went all weird, and that was that.
"He collapsed and I caught him. I was talking to him, trying to stop the blood. He was staring at the sky."
Medics soon arrived, but were unable to save Johnny.
The court heard McBride again contacted his ex admitting he had stabbed Johnny believing he had died.
Prosecutors accepted McBride had carried out the fatal attack "under provocation".
Lady Haldane deferred sentencing for reports.
