A woman told Oxford Crown Court she was raped while staying at a house in the city.
Max Wallace, 24, of Torres Square, Millwall, London, on June 29 denied raping the woman.
He said the woman, who cannot be named for legal reasons, had agreed to have sex with him.
The court heard that the alleged offence happened in the early hours of September 25 last year.
Ian Acheson, prosecuting, said Wallace and the alleged victim had been staying at the house, sharing a mattress in the lounge with another man.
He said the woman woke up to find the defendant having sex with her.
She told the court: "I tried to jump away, but he tried to get me back on to the mattress again."
She said after the alleged rape, Wallace made her shake his hand and promise not to tell anyone what had happened.
The woman left the house and called a friend who came to pick her up. She found her "hysterical and distraught".
Her friend took the woman to hospital, and the police were called.
The woman told the court the incident left her feeling "sick, dirty and empty".
She denied that she had agreed to sex with Wallace, or given him any hint she wanted sex.
The case continues.
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