Detectives are investigating after a 23-year-old university student said she was raped in Lancaster earlier this week.
Details of a sex assault in the early hours of Monday, March 3, were previously released by police.
Today, they confirmed the inquiry was an allegation of rape on a woman as she walked home from a night out in the city centre between midnight and 2.30am.
As she walked along Ashton Road she approached a man and asked him for directions.
Police said they had a conversation and the man then attacked her.
Detective Inspector Richard McCutcheon, from Lancashire Police, said: “We have a team of detectives working on the case and specially trained officers working with the victim.
“House-to-house and CCTV enquiries are ongoing and a number of items are being forensically examined to identify the offender.
“I would ask anyone who may have seen anybody acting suspiciously in the Bridge Road/Ashton Road area of Lancaster between the hours of midnight and 2.30am on Monday to come forward and contact us.
“Even the smallest piece of information could be crucial so we would urge anyone to contact us if they have any information at all that they think could assist the investigation.”
The man has been described as being in his early 20s, white, with wavy hair, about five feet ten inches tall and of average build.
Anyone with information can contact police on 101 quoting log number LC-20140303-0746.
Alternatively, information can be passed on via the independent charity Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org