The victim was walking towards the city centre along Lovell Park Road, near the flyover with the A64, when the attacked took place just after 5am today (August 10).
The victim managed to flee the scene and get away from the suspect, who is described as a white male in his early twenties.
He was wearing a grey and black hooded top and a black baseball cap.
Detective chief inspector Stuart Spencer, of Homicide Major Enquiry Team, said: “Enquiries are ongoing into this incident and the victim is being supported by specially trained officers.
“Given the time of this incident and its proximity to Leeds city centre it is likely that the suspect may have been seen in the town centre or indeed the streets around Lovell Park.
“If you saw someone fitting this description behaving suspiciously in or around the area of Lovell Park Road, or have any information, please contact Leeds CID via 101.”
Alternatively, call Crimestoppers anonymously on 0800 555 111.