Kathryn Mayorga, a former teacher and model, is raising questions about the validity of a confidentiality agreement and $375,000 (£292,537) hush money she received from the sports star in 2010.
US magistrate Daniel Albregts told Ms Mayorga’s lawyer that it will be up to a higher-level judge to decide if her effort to obtain more money advances will go to trial or be settled behind closed doors.
Mr Albregts handles filings and pre-trial arguments in the case, but Ronaldo’s lawyers want it dismissed or dealt with in private talks.
The judge said his preliminary review of settlement documents filed under seal in the civil lawsuit led him to agree with Ronaldo’s lawyers that the record should, at least for now, remain sealed.
Leslie Mark Stovall, Ms Mayorga’s lawyer, has declined to comment on the ruling.
Ms Mayorga, who lives in the Las Vegas area, gave consent through her lawyers to be identified last year.
She said in court documents she met the Portuguese footballer at a nightclub in 2009 and went with him and other people to his suite at the Palms Hotel and Casino, where he allegedly assaulted her in a bedroom.
Ronaldo, who is 34 and plays for the Italian side Juventus, maintains the sex was consensual.
US prosecutors said in July 2019 that Ronaldo would not face criminal charges over the sexual assault allegations.
Mr Stovall said in court he wanted communication records between Ronaldo and his lawyers prior to the 2010 settlement to answer Ms Mayorga’s questions about the legality of the contract.
The lawyer maintains that Ms Mayorga, then 25, had learning disabilities as a child.
He added the records he seeks would show Ronaldo’s legal team knew she was so distraught that she lacked the legal capacity to sign a non-disclosure agreement.
Ronaldo’s lawyers Kendelee Works and Peter Christiansen say there is no evidence Ms Mayorga was incapacitated or incapable of understanding what she was signing.
Ms Works said in court that the existence of the agreement and payment should never have been disclosed publicly, and added the contract calls for out-of-court arbitration to resolve the dispute.
Ronaldo’s lawyers maintain that 2017 news reports in Europe about the settlement and payment were based on electronic data that was illegally hacked, stolen and sold by cybercriminals.
They say they believe the documents have been altered and complain that Ms Mayorga’s lawsuit is damaging Ronaldo’s reputation.