Prince Harry could take the witness stand as soon as Wednesday in his High Court battle against Associated Newspapers Limited, the company behind the Daily Mail.
The duke is among several prominent figures pursuing legal action against ANL over alleged unlawful information gathering practices, including phone tapping and obtaining private records through deception.
Sir Elton John and his husband David Furnish have joined the case, alongside campaigner Baroness Doreen Lawrence, former Liberal Democrat politician Sir Simon Hughes, and actresses Sadie Frost and Liz Hurley.
Harry had been expected to testify on Thursday, but opening arguments from both sides wrapped up ahead of schedule on Tuesday.
Prince Harry set for earlier testimony as defence team brands case ‘threadbare’
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His barrister, David Sherborne, told the court he would "endeavour to have the Duke of Sussex here at 2pm tomorrow".
ANL has firmly rejected all allegations of wrongdoing and is mounting a robust defence against the claims.
The publisher's barrister, Antony White KC, told the court on Tuesday that the accusations were "threadbare" and had been filed outside the permitted timeframe.
He argued that journalists at the organisation had provided a "compelling account of a pattern of legitimate sourcing" for the more than 50 articles allegedly produced through unlawful methods.
The Duke of Sussex is one of seven prominent figures bringing the case, alongside Sir Elton John, David Furnish, Baroness Doreen Lawrence, actress Sadie Frost, Liz Hurley and former Liberal Democrat MP Sir Simon Hughes
| GETTYMr White dismissed references to payments made to private investigators as "examples of clutching at straws in the wind and seeking to bind them together in a way that has no proper analytical foundation".
In written submissions, the barrister maintained that all articles concerning the duke were sourced legitimately through contacts, press officers, publicists, freelance journalists and previous reports.
The claimants' barrister painted a picture of significant personal toll on the duke, telling the court that Harry's witness statement describes the distress and paranoia the situation has caused him.
David Sherborne said: "But given what we've seen, is it any wonder that he feels that way, or as he explains, that he feels he has endured a sustained campaign of attacks against him for having had the temerity to stand up to Associated in the way that he has so publicly done."
Associated Newspapers 'strongly denies' that there was any unlawful information gathering, including voicemail interception, directed at Prince Harry or his associates
| PAThe 14 articles at the centre of Harry's claim, published between 2001 and 2013, dealt primarily with his romantic relationships before meeting Meghan, the Duchess of Sussex.
Mr Sherborne described the coverage as "highly intrusive and damaging", focusing on relationships the duke "formed, or rather tried to form" during those years.
The lawyer made it clear that financial compensation was not the primary motivation for bringing the case to court.
He said: "It is not the claim for damages that brings these claimants here. It is the uncovering of the truth of what was done to them, and Associated taking accountability for that."
Prince Harry appeared in good spirits on Monday evening | GETTYThe barrister also addressed ANL's defence that the claims were submitted too late, describing it as a "potential life raft in a sea of unlawful information gathering" but asserting the publisher may not "be able to climb aboard" since all claims were filed within the required period.
Proceedings will resume at 10.30am on Wednesday, with Mr Justice Nicklin presiding.
The trial is expected to conclude in March, with a written judgement to be delivered at a later date.