Australian actor Rebel Wilson took out defamation insurance before she posted a series of allegedly slanderous social media posts about the star of her directorial debut, a court has been told.

The Pitch Perfect star directed, co-produced and starred in The Deb, a musical comedy set in rural NSW which was only recently released due to various legal battles.

She is being sued by the lead actor, Charlotte MacInnes, over social media posts claiming she confided in her that she felt uncomfortable with co-producer Amanda Ghost.

MacInnes has denied making the complaint to Wilson and said she has been seriously harmed by the older actor's suggestions she retracted the alleged comments in return for a lead role and a record deal.

"It it is a lie," her lawyer Sue Chrysanthou SC told the Federal Court on Monday.

"No such conversation occurred. That is a fabrication by Ms Wilson."

The social media posts are said to blame MacInnes for blocking the film's release with her lies and portray her as selfishly putting her own career ahead of the 300 cast and crew who worked on The Deb.

But it was outrageous to suggest her client had anything to do with delaying the film's release when Wilson instigated and spread the bad publicity, Ms Chrysanthou said.

Wilson took out defamation insurance with QBE after learning she would not be given writing credit for the film "so she could go ballistic on social media", she claimed.

Instead of checking in on MacInnes as an alleged victim of inappropriate behaviour, Ms Chrysanthou said the older actor made "grotesque" claims on her Instagram stories.

"This is how this bully, apparently this saviour of women, the protector of the harassed, responds," she said.

But Wilson raised her concerns with others even though she had doubts about the veracity of the alleged complaint, her lawyer Dauid Sibtain SC said.

The central issue is not whether she was a victim but instead whether she complained to Wilson and then changed her story, he said.

"The reason she did so is obvious ... to ensure her career as an actress and musician progressed by appeasing Ms Ghost," Mr Sibtain told the court.

The lure of future opportunities, which have since materialised as a lead role in a stage production and a record deal with a prestigious label, was sufficient motive, he claimed.

MacInnes says Wilson's social media posts damaged her professional reputation and created doubts about her trustworthiness before she could even enjoy the benefits of playing her first lead role in a film.

The up-and-coming actor is seeking aggravated damages for the serious harm caused as well as a court order preventing Wilson from repeating the claims.

Yet Mr Sibtain said her professional career has progressed since the social media posts were shared for 24 hours to Wilson's 11 million followers.

"She suffered no harm to her career at all," he told the court.

The actors avoided eye contact as they sat near each other in court, with Wilson occasionally scoffing through proceedings.

The Bridesmaids star praised the film as she entered the Federal Court on Monday morning for the first day of the nine day hearing.

"I love the movie. The Deb is so cute and amazing," she said.

The internationally acclaimed star wore a smile and neutral tones as she entered the courthouse after flying to Australia from the US over the weekend.

She and her wife are expected to give evidence next week.

The Deb premiered in 2024 but had been blocked from wider distribution by legal disputes.

The film was released in Australia on April 9, with some local reviews praising it as "joyous" and "filthy, fun, but most of all moving", while another said "many moments fall flat".