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
Hundreds of people do no know when they will be allowed back home after a 'serious incident' was declared in east London.
A Tube and rail strike planned for Wednesday evening could bring the capital to a standstill causing travel chaos for millions of commuters
The only Muslim survivor of the 7/7 terror attack in London has urged the country to stand together against Islamophobia.