Police and paramedics were called to Lavender Hill at around 3.30pm yesterday (October 21).
A 19-year-old was taken to hospital with stab wounds that were thought to be life-threatening.
A Met Police spokesperson has confirmed that he remains fighting for his life as his “condition remains the same” the next day.
There have been no arrests as police appeal to the public for information.
A spokesperson for the Metropolitan Police said: “At 15:26hrs on Tuesday, 21 October, officers attended Lavender Hill, Wandsworth, alongside the London Ambulance Service following reports of a stabbing.
“A 19-year-old was treated at the scene for stab wounds.
“He was taken to hospital with injuries believed to be life-threatening.
“We await an update on his condition.
“No arrests have been made, and police are urgently making enquiries.
“Anybody who witnessed the incident – or who has information – is urged to call 101, quoting crime reference 4781/21OCT.”