A woman was saved from being assaulted after a dog disturbed the culprit.
Police say the 18-year-old was walking along Fermaine Avenue in Broom Hill, Bristol, on Friday when she was grabbed by a man and pushed to the floor.
As he was opening his coat the dog, thought to be a spaniel, ran up to him. The man then fled the scene.
Officers say the attacker was 6ft tall and of a large build. He was wearing a knee-length coat with a black fur-trimmed hood.
Police are also trying to trace the dog's owner who may have seen the assault.