A 15-year-old boy killed a teenager with a "Rambo-style" knife during an argument over a phone charger, a court has heard.
Tyrone Hayman, 17, was found with a stab wound to the chest in Bedminster, Bristol, on 14 December.
The 15-year-old, who cannot be named for legal reasons, denies murder and said it was an accident during a "play fight" at Tyrone's flat.
It is Bristol Crown Court's first trial since the Covid-19 lockdown.
The court heard the defendant took out a "Rambo-style" knife and stabbed Tyrone once in the chest, causing fatal injuries.
Prosecutor Adam Vaitilingam QC told jurors: "The two of them had an argument over the use of a phone charger that they were both using to charge their phones.
"During the argument, the defendant picked up a knife and he stabbed Tyrone."
The court heard Tyrone ran out into Parson Street after being stabbed.
Paramedics were called and he was taken to Bristol Royal Infirmary, where he was pronounced dead.
Police later arrested the defendant, who had cycled away from the flat, and he was charged with murder.
Mr Vaitilingam said there was "no dispute" that the defendant had stabbed Tyrone but told jurors the boy claimed in a statement provided to police that it was an accident.
"He says he was holding the knife when Tyrone came towards him play fighting. He says Tyrone accidentally impaled himself on the knife," he said.
The court heard a girl in the flat with Tyrone and the defendant described the weapon as a "Rambo-style" knife.
She told police the knife, which has never been found, belonged to the defendant and he took it out of a holder before using it.
A post-mortem examination found Tyrone died from a single stab wound to the left side of his chest.
The trial continues.