Prince Andrew's accuser Virginia Giuffre is said to be set to hand over a legal document that the royal's legal team hopes will threaten her own case.
The document, more than a decade old, deals with her case against her sex abuser Jeffrey Epstein.
The Duke of York's legal team has demanded to unseal the document, which it claims will waive her right to pursue legal action against the royal.
However her legal team has rubbished the opposition's hopes, saying the 'release' relating to Epstein's sex abuse case does not apply to Prince Andrew.
Ms Giuffre accuses Andrew of forcing her to have sex with her at Epstein's associate Ghislaine Maxwell's home while she was underage.
The duke vehemently denies the allegations.
The ongoing legal battle currently playing out in New York had been mired in arguments over whether the royal had been properly served with Ms Giuffre's lawsuit.
The prince and his accuser have since agreed that service was effective as of September 21, according to a joint filing with the US District Court in Manhattan.
Subject to court approval, Andrew has until October 29 to formally respond to her lawsuit.
The agreement ended a monthlong effort by Andrew's legal team to block Ms Giuffre's lawsuit at the outset, rather than have the 61-year-old prince defend against it.
The duke is accused of forcing Ms Giuffre her to have sex around two decades ago, when she was underage, at the London home of Maxwell, Epstein's longtime associate.
Ms Giuffre's lawsuit also alleges Andrew abused her at Epstein's mansion in Manhattan and on the late billionaire financier's private island in the US Virgin Islands.
Andrew has not been charged with any crimes.
The document his lawyers are seeking to review is a 2009 settlement agreement from a lawsuit against Epstein in Florida, to determine whether it requires a dismissal of Ms Giuffre's case.
According to the Sun on Sunday, the document is a 'release' Andrew's legal team is hoping will exempt him from Ms Giuffre's lawsuit.
But her lawyers have reportedly branded it “irrelevant” and say the agreement releases lawyers, employees, agents and heirs from liability in connection with the Epstein case - not the duke.
Her lawyer, David Boies, reportedly said in a legal document filed in New York this week that he was happy to hand the document over to Andrew's team.
He said: “Although we believe that the release is irrelevant to the case against Prince Andrew, now that service has been accepted and the case is proceeding to a determination on the merits, we believe that counsel for Prince Andrew have a right to review the release and to make whatever arguments they believe appropriate based on it.
“Accordingly, we have given Mr Epstein’s Estate notice of Prince Andrew’s request and have asked the Estate to consent to our providing a copy of the release to Prince Andrew’s counsel.”
Ms Giuffre is seeking unspecified damages in her lawsuit against the Queen's second son.
Epstein, a registered sex offender, killed himself at age 66 in a New York jail while awaiting trial on sex trafficking charges.
Giuffre sued Andrew under a 2019 New York law that gave survivors of childhood sexual abuse a since-closed two-year window to sue their alleged abusers over conduct occurring many years or decades earlier.
Maxwell faces trial in New York in November to face charges she helped recruit and groom underage girls for Epstein to abuse.
She has pleaded not guilty.