A 22-year-old woman was sexually assaulted after she got off a bus in Greater Manchester.
The attacker followed the woman along Rippingham Road, Withington, after she left the bus at 0340 BST.
Police said he forced the woman into a house porch where he sexually assaulted her. A resident came to help her after the man fled when she screamed for help.
Police have appealed to anyone with information to contact them.
The attacker is described as white, in his late 20s to early 30s, of a slim build, with ginger or mousy-blonde wavy hair.
Det Con Rick Anderton said: "This young woman has suffered a traumatic ordeal and I want to assure her and anyone else who might be reading this story that we are doing everything we can to catch him.
"I would like to appeal to anyone who was in the area at about that time of night and perhaps saw this man hanging around to come forward.
"Your information in helping us track his movements could be key to finding him so please, if you do have any information, do speak out."
He said he was treating it as an isolated incident but urged people to be careful when walking home alone at night.