Michael Simon Wright, known as Simon, died in hospital
A teenage boy was stabbed to death during a row over £15, the Old Bailey has heard.
Michael Wright, 17, was killed on 19 February near Maryland station in Stratford, east London.
It was alleged Michael was stabbed in the stomach with a kitchen knife after he urged a 16-year-old boy to repay £15 he had borrowed for nightclub entry.
The defendant, who cannot be named, denies murder. He has claimed Michael "lunged forward" onto his knife.
Sallie Bennett-Jenkins QC, prosecuting, said six days before his death Michael had lent the defendant £20 to go clubbing.
She said the boy paid back £5, but refused to hand over the rest despite two approaches.
This led to a confrontation between the pair which left Michael fatally wounded.
Miss Bennett-Jenkins said: "Understandably, Michael had wanted his money back and tried to speak to him about it.
"There was a brief exchange before this defendant produced a large knife and inflicted the wound to Michael's stomach."
She continued: "There is no dispute he inflicted the fatal blow but we anticipate the defendant will say it was given in self-defence."
Miss Bennett-Jenkins urged jurors to try the case "in a cool and dispassionate manner", adding: "The loss of life is always tragic and never more so than when a young person has lost their life."
After his arrest the defendant told police Michael had previously threatened him and he was carrying a knife because he was frightened.
He allegedly told police that Michael was wielding a broken bottle when he accidentally lunged onto the knife.