The attack took place in Adelaide Close on the Moorlands Estate.
Scotland Yard said the victim was with his friend on the way to the friend's relative's house in Brixton when the attack happened.
The suspects were described as two young black men.
More top news
An unsettled weekend ahead - but Sunday should be dry and bright.
A petition with more than 100,000 signatures was handed in at Downing Street today calling for puppy farming to be banned.
The family said the three years the court cases have dragged on have not allowed them to mourn his death properly.