The promising chef, 22, from Chile, had been a guest at the Brunswick East party when he entered a bedroom where his victim was asleep at about 1am.

He lay beside his victim before touching her and having sex with her during an attack lasting between 10-15 seconds.

The victim could not remember why the chef suddenly stopped raping her, but it could have been when she moved her body and turned to look at him.

She had never met him before.

The chef quickly got up, dressed and left the room.

The victim then came out of the bedroom and identified the chef as the man who had just raped her.

The chef was found guilty by a County Court jury of two counts of rape and jailed for five years with a minimum of three years.

The sentencing judge said the evidence showed the victim had spent some hours at the party on May 24, 2013, but had not met or spoken to the chef.

"Although I accept what you did was opportunistic, you nonetheless set upon a young woman who was asleep in bed and proceeded to take advantage of the fact that she was asleep, and partially naked, to obtain sexual gratification," the judge told the chef.

"You must have known that she was asleep.

"You must have known that she could not be consenting to any level of sexual activity whilst in that state.

"It was as a result of her vulnerability, being both asleep and partially naked, and possibly suffering the effects of intoxication, that you set upon her in the hope that she might be compliant, or that you might obtain the sexual gratification you were after, from a woman who was possibly in a state where she might not be aware of what was happening to her."

The chef appealed his jail sentence and Court of Appeal Justices Robert Osborn and Phillip Priest agreed it was manifestly excessive, reducing the sentence to four years' jail with a minimum of two years.

In their recent judgment, Justice Osborn said the chef had no prior convictions and had travelled to Australia to improve his English and become a qualified chef.

He had arrived in Australia in 2012 and lived initially with a Chilean family for about six months before moving into a shared house with other students.

He undertook a training course at William Angliss Institute with considerable success, receiving a chef's scholarship in 2013 and 2014, and was working part-time as a hotel chef when arrested.

Justice Osborn said the chef's first trial in April 2015 ended in a hung jury, he lost his job and his bail was revoked.

The Immigration Department then cancelled his visa and he was eventually sent to Christmas Island detention centre for four months until his second trial began.

Justice Osborn said the sentencing judge was correct to accept that the rape was at the lower end of the range of seriousness because of the very short duration and extent of the incident in question.

"As the applicant [the chef] submits, the victim made clear in her evidence in chief that the entire offending was over in a matter of seconds," Justice Osborn said.

He said the chef's original jail sentence was manifestly excessive because of his youth, his previous good character, the brief duration of his offending, his high level of achievement as an overseas student, his isolation in prison since his family was in Chile, and the likelihood he would be held in protective custody given he had been bullied by other prisoners.