A teenager confronted her alleged rapist about whether he had confessed to his girlfriend about cheating with an underage girl, a jury has been told. 

The series of messages was detailed at the start of Lachlan Young's trial in the Victorian County Court on Thursday after he pleaded not guilty to raping the 16-year-old girl. 

Young, 24, met the teen at a small house party in the Ballarat suburb of Sebastopol on February 4, 2024, prosecutor Andrew Buckland told the jury. 

The pair chatted, exchanged Snapchat details and as the other partygoers went to bed, the local man asked the teen if she "wanted to do things", the jury was told. 

The girl said no because she was tired and she went to bed but they continued to send Snapchat messages to each other, Mr Buckland said.

The girl told Young she was only 16 and he allegedly still asked to have sex with her, saying "just five minutes and I'll make it worth it". 

The teen agreed to meet Young in the backyard and she consented to some sexual touching.

But when Young said "wanna f***", she replied "no", the jury was told. 

It's alleged Young ignored the girl's refusal and instead raped the teen without wearing a condom.

He then allegedly told the girl: "You should probably go back inside before people look for you." 

The girl disclosed the alleged rape to her friend the next morning and confronted Young a week later in a series of Snapchat messages.

"How's ya missus?" the girl asked the Sebastopol man.

"How would she feel about you f****** an underage (girl) and cheating on her?" 

The jury was told she sent a follow-up message on February 29, asking Young again if she had told his girlfriend about the alleged rape.

Young responded to the teen on March 1, asking her, "what are you on about?"

The girl called Young pathetic and said he had sex with her after she had said no.

Young then blocked the teen on Snapchat.

The girl reported the alleged rape to a wellbeing counsellor at her school, who then contacted police on her behalf on March 18.

The teen provided a statement to detectives on April 2.

Defence barrister Glenn Casement told the jury Young was innocent of rape and the girl had made a false allegation.

He argued the girl's claims should not be trusted and the jury should scrutinise her evidence.

"Her credibility and reliability will be utterly central concepts in this trial," Mr Casement said.

The trial before Judge Caitlin English is expected to conclude within a week. 

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