Police were called at approximately 17:00 on the 20th December after a 17-year-old reported being assaulted by a man.
The attack happened at the junction of Goat Road and London
Road near to the Crown of Mitcham in Merton.
The teenager self-presented at a south London hospital where
he underwent surgery and remains in a stable condition.
Officers want to hear from anyone who saw anything
suspicious in the area at or around the time of the incident.