Sutton police are hunting for an attacker after a woman was randomly assaulted in a park.
The incident took place in Mellows Park, Wallington, around 10-10.45pm on Sunday, August 3.
After the attack the man is believed to have made off towards nearby Plough Lane.
He is described as black, aged between 18 and 35, and of average height and build.
The attacker was a wearing a black woolly hat and a dark top.
Officers are keen to speak to a group of youngsters who were in the park at the time.
Detective constable Kate Elson from Sutton police said: “The victim was convinced she was going to be stabbed and remains in a state of shock.
“Her attacker needs to be caught and we are urging anyone with information to come forward and help us.”
If you have any information contact police on 0208 649 4122.
Alternatively call Crimestoppers anonymously on 0800 555 111.