A 21-year-old man murdered a teenager by knifing him in the chest after an argument in a Sydenham street, a court has heard.

Marley Lucas delivered the fatal blow, which killed Nathan Murray, 18, after confronting him in Sydenham High Street at lunchtime on June 1, this year, the Old Bailey was told today.

Lucas, of Champion Road, Sydenham, used a broad-bladed knife to stab Mr Murray - leaving him with a 17cm deep wound - before driving away in a black Fiat Punto at speed.

Prosecutor Timothy Cray QC told the court: “He [the defendant] got out of the car, produced a large knife and stabbed Nathan Murray in the centre of his chest.”

Two days after the stabbing, Lucas was arrested on suspicion of murder in Chingford, north London, but made no comment during his police interviews.

He later admitted being present in Sydenham High Street that day and stabbing Mr Murray but denies murder.

Mr Cray told the jury: “In the run up to the trial he [the defendant] has accepted that he was present at the scene and that he stabbed Nathan Murray.”

A jury of eight women and four men were sworn in for the trial of Lucas, who appeared in the dock dressed in a white shirt, blue striped tie and blue jumper, which is expected to last two weeks.

Mr Murray had enjoyed a normal Monday morning by going to the gym and eating a meal with friends in a Sydenham café before he was stabbed, the jury heard.

The jury were shown CCTV footage of Mr Murray and three friends in Sydenham High Street before and after he was stabbed.

Lucas, who driving through the area, had spotted Mr Murray walking along the pavement with his friends and turned the car around so he could catch up with the teenager and confront him.

Mr Cray said the speed of the attack was such that nobody seemed to be immediately aware of the knife, which was wrapped in cloth.

“Arguments between people on the street - that is life. People get worked up but what the defendant did with the knife takes this into a different league,” Mr Cray told the court.

“Some sort of argument started and as a result of that he delivered one blow into Nathan's chest."

Mr Cray continued: "Whatever that 25 second argument was about, there was no need for him [the defendant] to kill Nathan.

"Young men, all over this city, can fall out and get annoyed but this defendant had many better choices than the one he made, which was to stab Nathan Murray to death."

The trial continues.